introduction to earthquake resistant analysis & design...
TRANSCRIPT
![Page 1: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/1.jpg)
1
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Lecture-10
Introduction to Earthquake Resistant Analysis & Design
of RC Structures (Part II)
By: Prof Dr. Qaisar Ali
Civil Engineering Department
UET Peshawar
www.drqaisarali.com
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Topics Addressed
Load Combinations
Analysis using software
Gravity vs. Earthquake Loading
ACI Special Provisions for Seismic Design
ACI Special Provisions for Special Moment Resisting Frame (SMRF)
ACI Special Provisions for Intermediate Resisting Frame (IMRF)
Miscellaneous Considerations
Design Example
References
2
![Page 2: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/2.jpg)
2
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
UBC-97 Load Combinations
UBC-97 adopts load combinations and strength reduction
factors of ACI 318-99.
According to UBC-97, earthquake combinations shall be
multiplied by 1.1 for concrete structures.
3
Load Combinations
UBC-97 (section 1612.2.1)
Load Combinations Strength Reduction Factors
1.4D 0.9 (flexure)
1.4D + 1.7L 0.85 (Shear)
1.2D + 0.5L ± 1.0E 0.70 (Tied )
0.9D ± 1.0E 0.75 (Spiral)
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
UBC-97 Load Combinations
Definition of E in UBC-97
According to section 1630.1.1 of UBC-97 (section 5.30.1.1 of BCP SP-
2007), E is given as:
E = ρEh + Eν
Eh = Horizontal component of the earthquake load (storey Force).
Eν= Vertical component of the earthquake ground motion.
In most of the cases, ρ ≈ 1, so,
E = Eh + Eν
Now, Eν = 0.5CaID, therefore,
E = Eh + 0.5CaID
4
Load Combinations
![Page 3: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/3.jpg)
3
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
UBC-97 Load Combinations
Therefore, the following load combinations of UBC-97 are
generated:
1.1[1.2D + 0.5L ± 1.0 (Eh + 0.5CaID)} ]…..……(i)
1.1[0.9D ± 1.0 (Eh + 0.5CaID)] …………………(ii)
NOTE: D, L and Eh represents load effects axial force, shear, and
bending moment due to respective loads.
5
Load Combinations
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
UBC-97 Load Combinations
As an example let’s write UBC Load Combinations for
following seismic zone data:
Seismic Zone: 2B
Soil type: SD
Importance factor (I)= 1
For seismic zone 2B and soil type SD, Seismic coefficient Ca = 0.28
With this data, following UBC-97 load combinations are
obtained:
6
Load Combinations
![Page 4: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/4.jpg)
4
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
UBC-97 Load Combinations
1.1[1.2D + 0.5L ± 1.0 (Eh + 0.5CaID)]…..……(i)
1.1[1.2D + 0.5L ± 1.0 (Eh + 0.5 × 0.28 × 1.00 ×D)]
1.32D + 0.55L ± 1.1Eh ± 0.154D
1.474D + 0.55L ± 1.1Eh …………….. (ia)
1.166D + 0.55L ± 1.1Eh …………….. (ib)
7
Load Combinations
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
UBC-97 Load Combinations
Similarly,
1.1[0.9D ± 1.0 (Eh + 0.5CaID)] …………………(ii)
1.1[0.9D ± 1.0 (Eh + 0.5 × 0.28 × 1.00 ×D)]
0.99D ± 1.1Eh ± 0.154D
1.14D ± 1.1Eh …………….. (iia)
0.84D ± 1.1Eh ……………. (iib)
8
Load Combinations
![Page 5: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/5.jpg)
5
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
UBC-97 Load Combinations
Finally, following six load combinations would be used in design.
1.4D
1.4D+1.7L
1.474D + 0.55L ± 1.1Eh …………….. (ia)
1.166D + 0.55L ± 1.1Eh …………….. (ib)
1.14D ± 1.1Eh …………….. (iia)
0.84D ± 1.1Eh ……………. (iib)
9
Load Combinations
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Load Combinations in Other Codes
ACI 318-14
1.4D
1.2D+1.6L
1.2D + 1.0L ± 1.0E
0.9D ± 1.0E
Note: This “E” must be calculated using IBC code.
BCP SP-2007
BCP has same combinations as UBC-97.
10
Load Combinations
![Page 6: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/6.jpg)
6
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Compatibility of BCP (UBC) and ACI
BCP chapter 7 can be used for earthquake resistant design of
RC structures using load combination and Strength Reduction
Factors of chapter 5 of BCP (UBC 97 load combinations).
To maintain compatibility in the usage of BCP code, analysis is
done using load combinations of UBC-97. Design can be done
using:
UBC-97 design procedure of chapter 19 which is ACI 318-99.
ACI 318-14 using load combinations and strength reduction factors of UBC-
97.
11
Load Combinations
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Following steps are followed to apply load combinations:
The structure is analyzed for unamplified load cases separately e.g.,
Analysis for unamplified dead load (1.0D),
Analysis for unamplified live load (1.0L)
Analysis for unamplified lateral storey load cases (1.0Eh).
Load effects obtained for each load case are multiplied with amplification
factors and combined as per code load combination requirements.
With this approach, the structure has to be analyzed only for each load case.
After analysis, any load combinations can be performed with load cases.
12
Load Combinations
![Page 7: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/7.jpg)
7
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 1: Apply Load combinations to analysis results of the encircled bay of
the given structure.
13
Load Combinations
20 ft20 ft20 ft20 ft
15 ft
15 ft
15 ft
fc′ = 3 ksify = 40 ksi
SDL = 40 psfLL = 60 psf
SDL = 40 psfLL = 60 psf
SDL = 40 psfLL = 60 psf
Seismic Zone: 2BSoil: SDSlab: 6″
Beams:12″ × 18″Columns: 12″
BAY
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 1
Following UBC-97 load combinations for zone 2B and soil SD are
used:
1.4D+1.7L
1.474D + 0.55L ± 1.1Eh …………….. (ia)
1.166D + 0.55L ± 1.1Eh …………….. (ib)
1.14D ± 1.1Eh …………….. (iia)
0.84D ± 1.1Eh ……………. (iib)
14
Load Combinations
![Page 8: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/8.jpg)
8
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 1
Sign convention
15
Load Combinations
Bent left (+) Bent right (−)
BM Sign convention for column
Bent down (+) Bent up (−)
BM Sign convention for beam
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 1
16
Load Combinations
E
-17 -17
9
-0.5
1.0
22
-22-39
37
-37
33
1.0D 1.0L 1.0E −1.0E
39
-37
37
-33
-22
22
1.4D + 1.7L
-89 -89
52
-2.8
4.5
1.474D + 0.55L + 1.1E
-97 -97
43
-45
44
-43
40
1.166D + 0.55L − 1.1E
-79 -29
35
41
-37
41
-37
1.14D + 1.1E
-25 -73
31
-45
43
-42
39
0.84D − 1.1E
-60 -12
22
42
-39
40
-35
-97 -9752
-45 -43
Envelop
44 -37
For higher zone, this value might become positive
E
Bent left (+) Bent right (−)
BM Sign convention for column
Bent down (+) Bent up (−)
BM Sign convention for beam
-43 -43
26
-1.4
2.0
![Page 9: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/9.jpg)
9
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Case Study 1: Study on Results of Analysis using UBC and ACI
Load Combinations.
17
Load Combinations
20 ft20 ft20 ft20 ft
15 ft
15 ft
15 ft
fc′ = 3 ksify = 40 ksi
SDL = 40 psfLL = 60 psf
SDL = 40 psfLL = 60 psf
SDL = 40 psfLL = 60 psf
Seismic Zone: 2BSoil: SDSlab: 6″
Beams:12″ × 18″Columns: 12″
Portion of frame considered
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Case Study 1: Following load combinations for zone 2B and soil
SD are used:
In ACI load combination, “E” is as per IBC. In this example E is
taken as per UBC with vertical component ignored.
18
Load Combinations
UBC-97 Load Combinations:
1.4D+1.7L
1.474D + 0.55L + 1.1E
1.166D + 0.55L − 1.1E
1.14D + 1.1E
0.84D − 1.1E
ACI 318-14 Load Combinations:
1.2D+1.6L
1.2D + 1.0L + 1.0E
1.2D + 1.0L − 1.1E
0.9D + 1.0E
0.9D − 1.0E
![Page 10: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/10.jpg)
10
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Case Study 1
19
Load Combinations
Bent left (+) Bent right (−)
BM Sign convention for column
Bent down (+) Bent up (−)
BM Sign convention for beam
-17 -17
9
-0.5
1.0
22
-22-39
37
-37
33
1.0D
1.0L
1.0E
−1.0E
Analysis Results for Unamplified Individual load Cases
39
-37
37
-33
-22
22
-43 -43
26
-1.4
2.0
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Case Study 1
20
-89 -89
52
-2.8
4.5
1.4D + 1.7L (UBC-97) 1.2D + 1.6L (ACI-318-14)
-79 -79
46
-2.5
4.0
Load combination 1
Load Combinations
![Page 11: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/11.jpg)
11
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Case Study 1
21
1.474D + 0.55L + 1.1E (UBC-97) 1.2D + 1.0L + 1.0E (ACI-318-14)
-47-91
40
-41
40
-39
36
-48-97
43
-45
44
-43
40
-91
-47
40
1.2D + 1.0L − 1.0E (ACI-318-14)
37
-34
35
-30
1.166D + 0.55L − 1.1E (UBC-97)
-84
-35
35
41
-38
39
-33
Load combination 2 & 3
Load Combinations
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Case Study 1
22
1.14D + 1.1E (UBC-97) 0.9D + 1.0E (ACI-318-14)
-61
-17
23
0.9D − 1.0E (ACI-318-14)
38
-35
36
-31
-17-61
23
-40
39
-38
35
-25-73
30
-44
43
-42
39
-60
-12
22
42
-39
39
-35
Load combination 4 & 5
Load Combinations
0.84D − 1.1E (UBC-97)
![Page 12: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/12.jpg)
12
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Case Study 1: Conclusions
For the given frame, except gravity load combination 2, there is no significant
difference between UBC-97 and ACI 318-14 load combination results.
However in some cases it may be more.
Note that in each case, strength reduction factors are different. Therefore,
there will be difference in reinforcement as well.
Caution about use of load combination in SAP2000: Before designing in SAP2000,
make sure that combinations used are the same as used in the relevant code.
23
Load Combinations
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: Complete Example using Approximate Analysis
24
Load Combinations
20 ft20 ft20 ft20 ft
15 ft
15 ft
15 ft
fc′ = 3 ksify = 40 ksi
SDL = 40 psfLL = 60 psf
SDL = 40 psfLL = 60 psf
SDL = 40 psfLL = 60 psf
Seismic Zone: 2BSoil: SDSlab: 6″
Beams:12″ × 18″Columns: 12″
![Page 13: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/13.jpg)
13
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: E-W Frame to be analysed. Lateral load from Static
Lateral Force Procedure are shown.
25
F3 =23 kips
l1=20 ft l2=20 ft l3=20 ft
h=10.5 ft
F2 =15.5 kips
F1 = 7.74 kips
l4=20 ft
h=10.5 ft
h=10.5 ft
Load Combinations
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: Analysis Results for 1.0D
26
Column Moments
Beam Moments
Load Combinations
![Page 14: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/14.jpg)
14
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: Analysis Results for 1.0L
Column Moments
Beam Moments
Load Combinations
27
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Applications of Load Combinations
Example 2: Analysis Results for 1.0E
Load Combinations
28
![Page 15: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/15.jpg)
15
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: Analysis Results for −1.0E
Load Combinations
29
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: Analysis Results for 1.2D+1.6L
Column Moments
Beam Moments
Load Combinations
30
![Page 16: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/16.jpg)
16
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Applicationn of Load Combinations
Example 2: Analysis Results for 1.2D+1.0L+1.0E
Column Moments
Beam Moments
Load Combinations
31
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: Analysis Results for 1.2D + 1.0L − 1.0E
Column Moments
Beam Moments
Load Combinations
32
![Page 17: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/17.jpg)
17
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: Analysis Results for 0.9D + 1.0E
Column Moments
Beam Moments
Load Combinations
33
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of Load Combinations
Example 2: Analysis Results for 0.9D − 1.0E
Column Moments
Beam Moments
Load Combinations
34
![Page 18: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/18.jpg)
18
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Application of load Combinations
Example 2: Envelop Used For Design & Comparison with SAP
Column Moments
Beam Moments
Load Combinations
74 52 31 52 74
55 62 52 62 55
91 133 123 133 91
-74 -109 -88 -88 -88 -88 -109 -74
78 58 58 78
-100 -135 -114 -114 -114 -114 -135 -10078 58 58 78
-146 -181 -160 -160 -160 -160 -181 -14678 58 58 78
10 1022 22
56 564848 484837 37
54 22 21 22 54
56 42 37 42 56
85 81 77 81 85
-38 -60 -80 -71 -71 -80 -60 -38
84 36 36 84
-72 -93 -86 -85 -85 -86 -93 -7250 37 37 50
-97 -123 -109 -105 -105 -109 -123 -9754 37 37 54
6 6
46 10 10 463 10 10 3
35
Approximate Analysis Envelop SAP2000 Envelop
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Comparative study between gravity and earthquake load analysis
for various zones of the given structure using SAP2000.
36
Gravity vs. Earthquake Loading
20 ft20 ft20 ft20 ft
15 ft
15 ft
15 ft
The study has been done
using SAP2000 using ACI
318-14 load combinations
and is done for all
seismic zones. The study
has been done on the
same 4 by 3 (20′×15′)
panel building.
![Page 19: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/19.jpg)
19
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
The objective of this study is to determine for the given 3D
structure:
Bending moment due to gravity loads
Bending moments due to earthquake loads from zone 1 to 4.
Compare the bending moments to see the variation in bending
moments due to change in loading.
Compare the reinforcement requirement due to change in loading.
37
Gravity vs. Earthquake Loading
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Gravity Load Analysis (1.2D+1.6L) for all seismic zones
34-50
51
-80 -75 -73
37
-36
1.2D+1.6L
44
-38
-2-38
54
-85 -79 -71
36
Gravity vs. Earthquake Loading
38
![Page 20: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/20.jpg)
20
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Combinations for Zone 1
11-21
35
-65 -41 -59
25
-16
1.2D+1.0L+1.0E
1.2D+1.0L−1.0E
34-46
31
-43 -60 -39
25
-32
36
-31
22
-19
-35
32
-5
54
-95 -51 -80
31
-60
41
-51 -86 -42
33
0.9D+1.0E
0.9D−1.0E
4-10
27
-48 -25 -44
25
-8
13
-12
-329
32
-61 -19 -52
17
27-36
21
-27-44 -24
18
-25
27
-23
32-45
22
-18 -55 -15
19
Gravity vs. Earthquake Loading
39
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Combinations for Zone 2A
8 -19
48
-89 -47 -80
33
-16
1.2D+1.0L+1.0E
25
-22
-60
50-66
40
-49 -81 -45
33
-46
51
-43
64
17
59
-113 -30 -95
33
-83
41
-33 -100 -27
37
-5 0
28
-57 -18 -52
18
-2
0.9D+1.0E
8
-7
-6132
40
-79 -5 -67
19
37-46
21
-18 -52 -16
19
-32
33
-28
63-68
23
0 -69 0
22
0.9D−1.0E1.2D+1.0L−1.0E
Gravity vs. Earthquake Loading
40
![Page 21: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/21.jpg)
21
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Combinations for Zone 2B
2-13
50
-94 -42 -85
33
-12
1.2D+1.0L+1.0E
21
-19
-77
1.2D+1.0L−1.0E
56-72
40
-44 -86 -40
34
-50
54
-45
81
0.9D+1.0E
0.9D−1.0E
-116
30
-63 -13 -56
19
-2
4
-4
-80
46
-90 3 -77
20
42-53
22
-12 -57 -12
20
-36
37
-30
80-82
24
10 -78 9
24
-31
63
-123 -21 -105
33
-97
41
-22 -109 -18
38
Gravity vs. Earthquake Loading
41
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Combinations for Zone 3
1.2D+1.0L+1.0E
1.2D+1.0L−1.0E
64-81
39
-37 -92 -34
36
-56
59
-49
104
-16-5
-4
53
-101 -36 -91
33
-6
16
-10049
70
-138 -15 -117
36
-116
42
-8 -121 -5
40
0.9D+1.0E
0.9D−1.0E
0-18
14
32
-70 -7 -63
20
7
0
-10164
49
-105 15 -89
23
50-61
22
-5 -63 -5
21
-31
42
-34
104-101
26
24 -90 22
28
Gravity vs. Earthquake Loading
42
![Page 22: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/22.jpg)
22
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Combinations for Zone 4
1.2D+1.0L+1.0E
1.2D+1.0L−1.0E
71-89
40
-29 -97 -27
35
-61
64
-53
127
-11
-13 3
54
-108 -29 -98
33
-1
12
-12268
78
-152 -4 -130
37
-134
42
6 -132 6
44
0.9D+1.0E
2-26 23
35
-77 0 -69
20
12
-5
-12383
58
-119 26 -102
21
0.9D−1.0E
58-70
23
1 -69 0
22
-47
46
-38
126-119
29
39 -101 34
34
Gravity vs. Earthquake Loading
43
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Beam Moment Comparison for all zones
A
B
(A) (B)
Gravity vs. Earthquake Loading
44
Story 2
![Page 23: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/23.jpg)
23
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Beam Moment Comparison for all zones
A
B
(A) (B)
Gravity vs. Earthquake Loading
45
Story 1
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Beam Moment Comparison for all zones
C
(C) (F)
F
Gravity vs. Earthquake Loading
46
Story 2
![Page 24: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/24.jpg)
24
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Comparison for all zones
C F
(C) (F)
Gravity vs. Earthquake Loading
47
Story 1
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Beam Moment Comparison for all zones
E
(E)
Gravity vs. Earthquake Loading
48
Story 2
![Page 25: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/25.jpg)
25
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Comparison for all zones
E
Gravity vs. Earthquake Loading
(E)
49
Story 1
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Column Moment Comparison for all zones
Top moment
Gravity vs. Earthquake Loading
50
![Page 26: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/26.jpg)
26
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Case Study 2
Conclusions
The moments in almost all cases increases due to lateral loads in a
progressive manner from top to bottom and from low to high zone.
However, there is no significant change in beam mid span positive
moments for all zones.
Within a storey, exterior negative moment in a beam increases more
than that of interior negative moments in the same seismic zone.
Positive end moments in beams, especially in lower stories, may
become significant in higher seismic zones.
Gravity vs. Earthquake Loading
51
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
ETABS
Following slides present broad steps required to perform analysis.
52
Analysis & Design Using FEA Software
![Page 27: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/27.jpg)
27
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
1. After completing the modeling, gotoOption → Preferences → Concrete Frame Design
Analysis & Design Using FEA Software• ETABS
Select UBC-97 so that UBC load combinations can be generated
3. Goto Define → Special Seismic Load Effects and select from two options based on requirement:
(i) Include Special Seismic Design Data(ii) Do Not Include Special Seismic Design Data
Option (i) is normally selected.
Vertical component of earthquake loads can be included from this option.
Vertical component of earthquake loads can also be neglected if acceptable.Goto Define Load Add Default Design
Combos to Generate load combinationsSelect Concrete Frame Design to generate load combinations for concrete
material
Goto Define → Load Combinations to see the generated Load combinations
Click Modify Button to see details of load combinationsLoad Combination details
(Without inclusion of vertical component of earthquake load)
Load combination including vertical component of earthquake load
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
SAP2000
Following slides present broad steps required to perform analysis.
54
Analysis & Design Using FEA Software
![Page 28: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/28.jpg)
28
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Analysis & Design Using FEA Software• SAP2000
After completing the structural model, go to Define Load casesand all required load patterns.Earthquake load pattern should be defined as discussed inprevious lecture
Defined Load patternsNote: UBC 97 used for earthquake load definition.
Go to Design Concrete Frame Design View/ Revise Preferences to select code for design.
To generate load combinations select the code. As UBC is used for earthquake definition therefore select UBC.
Go to Define load Combinations to generate Load combinations as per UBC-97
Sometimes the desired load combinations might not match the required code combinations, therefore all combinations should be checked before final design.After this, the model is ready for analysis and design as per UBC-97.
In a second option, To perform analysis and design as per BCP, manually define all load combinations as per UBC-97 in Define Load Combination section.Then go to design Concrete Frame Design View/ Revise Preferences and change design code to ACI 318-05.Change the strength reduction factors as per UBC i.e., Φ for shear and torsion = 0.85 instead of 0.75.
Option 1Option 2
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
The principal goal of the Special Provisions is to ensure adequate
toughness under inelastic displacement reversals brought on by
earthquake loading.
The provisions accomplish this goal by requiring the designer to
provide for concrete confinement and inelastic rotation capacity.
No special requirements are placed on structures subjected to low or
no seismic risk.
Structural systems designed for high and moderate seismic risk are
referred to as Special and Intermediate respectively.
ACI Special Provisions for Seismic Design
56
![Page 29: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/29.jpg)
29
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Based on moment resisting capacity, there are three types of RC
frames,
SMRF (Special Moment Resisting Frame),
IMRF (Intermediate Moment Resisting Frame),
OMRF (Ordinary Moment Resisting Frame).
Some general requirements will be presented first, which are
common to all frames. Specific requirements for each type of frame
are presented later on.
ACI Special Provisions for Seismic Design
57
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
General Requirements
Concrete in members resisting earthquake induced forces
Min f’c = 3000 Psi (cylinder strength) for all types
No maximum limit on ordinary concrete
5000 psi is maximum limit for light weight
ACI Special Provisions for Seismic Design
58
![Page 30: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/30.jpg)
30
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
General Requirements
Reinforcement in members resisting earthquake induced forces
Grade 60, conforming to ASTM A 706 (low alloy steel)
Grade 40 or 60, conforming to ASTM A 615 (billet steel) provided that
Fy (actual) – Fy (specified) ≤ +18 Ksi
Actual Ultimate / Actual Fy ≥ 1.25
ACI Special Provisions for Seismic Design
59
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
General Requirements
Hoops, Ties and Cross Ties
Confinement for concrete is provided by transverse reinforcement
consisting of stirrups. hoops, and crossties.
To ensure adequate anchorage, a seismic hook (shown in figure) is used
on stirrups, hoops and crossties .
ACI Special Provisions for Seismic Design
(Seismic Hook)
60
![Page 31: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/31.jpg)
31
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
General Requirements
Hoops, ties and Crossties: Advantages
Closely spaced horizontal closed ties in column help in three ways:
i. they carry the horizontal shear forces induced by earthquakes, and thereby
resist diagonal shear cracks,
ii. they hold together the vertical bar and prevent them from excessively
bending outwards (in technical terms, this bending phenomenon is called
buckling), and
iii. they contain the concrete in the column. The ends of the ties must be bent
at 135° hooks. Such hook ends prevent opening of hoops and
consequently buckling of concrete and buckling of vertical bars.
ACI Special Provisions for Seismic Design
61
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provisions for Flexural Members
These provision applies to flexural members with:
Factored axial compressive force Agf’c/10.
Note: These provisions generally apply to beams because axial load on beams
is generally less than Agfc′/10.
However they are also applicable to columns subjected to axial load less
than Agfc′/10.
ACI Provisions for Special Moment Resisting Frames (SMRF)
62
![Page 32: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/32.jpg)
32
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provisions for Flexural Members
1. Size: The members must have:
a. clear span-to-effective-depth ratio of at least 4, (Ln/d ≥ 4)
e.g., for Ln = 15 ft, d = 16″, Ln/d = 15 × 12/16 = 11.25 > 4, O.K.
b. width-to-depth ratio of at least 0.3, b/d ≥ 0.3
e.g., for width (b) = 12″ and depth (h) = 18″, b/h = 12/18 = 0.67 > 0.3, O.K.
c. web width of not less 10 inches.
ACI Provisions for Special Moment Resisting Frames (SMRF)
63
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provisions for Flexural Members
2. Flexural Reinforcement
ACI Provisions for Special Moment Resisting Frames (SMRF)
Asl−
Asl+ (Asl−)/2
As− or As+ (at all section) (maximum of As at either joint)/4
Asr−
Asr+ (Asr−)/2
rmin = 3f’c/fy, 200/fy (at critical sections)
rmax = 0.025 (at critical sections)
Min. 2 bars continuous at all sections
64
![Page 33: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/33.jpg)
33
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provisions for Flexural Members
3. Transverse Reinforcement
ACI Provisions for Special Moment Resisting Frames (SMRF)
s
d/4
8 smallest longitudinal bar diameter
24 hoop bar diameter
12” 2”
≥ 2h ≥ 2hs d/2
Column
Column
65
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provisions for Flexural Members
4. Lap Splice
ACI Provisions for Special Moment Resisting Frames (SMRF)
Lap splice length =1.3 ld = 1.3 0.05 (fy/ √fc′)db
50 db for fc′ 3 and fy 40 ksi
70 db for fc′ 3 and fy 60 ksi
Spacing of stirrups Least of d/4 or 4 inches
Lapping prohibited in regions where longitudinal bars can yield in tension
Lapping of Longitudinal bars
≥ 2h ≥ 2h
66
![Page 34: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/34.jpg)
34
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provisions for Flexural Members
Mechanical Splice of Longitudinal Reinforcement
Mechanical Splices shall conform to 18.2.1.
Section 18.2.8.1 says that welded splice shall conform to 25.5.7
which states “A full mechanical splice shall develop in tension or
compression, as required, at least 125 % of the specified yield
strength (fy) of the bar.
ACI Provisions for Special Moment Resisting Frames (SMRF)
67
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provisions for Flexural Members
Welded Splice of Longitudinal Reinforcement
Welded Splices shall conform to 25.5.7.
Section 18.2.8.1 says that welded splice shall conform to 25.5.7
which states “ A full welded splice shall develop at least 125 % of
the specified yield strength (fy) of the bar.
ACI Provisions for Special Moment Resisting Frames (SMRF)
68
![Page 35: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/35.jpg)
35
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for Frame Members Subjected to Bending and Axial Load
The provision applies to members with:
Factored axial compressive force > Agf’c/10
ACI Provisions for Special Moment Resisting Frames (SMRF)
69
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for Frame Members Subjected to Bending and Axial Load
1. Size
a) Each side at least 12 inches
b) Shorter to longer side ratio ≥ 0.4.
i.e. 12/12, 12/18, 12/24 OK; but 12/36 not O.K
ACI Provisions for Special Moment Resisting Frames (SMRF)
70
![Page 36: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/36.jpg)
36
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for Frame MembersSubjected to Bending and AxialLoad
2. Longitudinal Reinforcement
ACI Provisions for Special Moment Resisting Frames (SMRF)
0.01 rg 0.06
Clear span, hc
71
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for FrameMembers Subjectedto Bending andAxial Load
3. Trans. Rein.
ACI Provisions for Special Moment Resisting Frames (SMRF)
h2
h1
s 0.25 (smaller of h1 or h2)
6 long. bar dia.
so
s 6 long. bar dia.
6”
lo
lo Larger of h1 or h2
Clear span/6
18”
72
![Page 37: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/37.jpg)
37
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for Frame Members Subjected to Bending and Axial Load
3. Trans. Rein.
ACI Provisions for Special Moment Resisting Frames (SMRF)
4” ≤ so = 4 + [(14 – hx)/3] ≤ 6”
hx = max. value of hx on all column faces
hx 14”
hx hx hx
hx
hx
6db 3” 6db extension
Alternate90-deg hooks
Provide add.trans. reinf. if thickness > 4”
73
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for Frame Members Subjected
to Bending and Axial Load
4. Lap Splice
ACI Provisions for Special Moment Resisting Frames (SMRF)
Tension lap splicewithin center half ofmember length
Lap splice length =1.3 ld = 1.3 0.05 (fy/ √fc′)db
50 db for fc′ 3 and fy 40 ksi
70 db for fc′ 3 and fy 60 ksi
Spacing of ties in lap splice not more than smaller of d/4 or 4″
74
![Page 38: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/38.jpg)
38
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Joints of Special Moment Frame
ACI Provisions for Special Moment Resisting Frames (SMRF)
Beam
Column
Beam Column Joint
Column ties (with 135o) hook continued through joint(ACI 25.3.4)
75
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Joints of Special Moment Frame
Successful seismic design of frames require that the
structures be proportioned so that hinges occur at locations
that least compromise strength. For this, “weak Beam-strong
column” approach is used.
After design, the member capacities are calculated based
on designed section.
Column flexural capacity > Beam flexural capacity
ACI Provisions for Special Moment Resisting Frames (SMRF)
76
![Page 39: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/39.jpg)
39
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Joints of Special Moment Frame
Minimum Flexural Strength of Column at Joint
M-nb,r
M+nc,t
M-nc,b
M+nb,r
M-nb,l
M+nc,b + M-
nc,t 6(M+nb,l + M-
nb,r)/5
M-nc,t
M+nc,b
M+nb,l
M-nc,b + M+
nc,t 6(M-nb,l + M+
nb,r)/5
ACI Provisions for Special Moment Resisting Frames (SMRF)
77
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Joints of Special Moment Frame
To prevent beam column joint cracking, ACI Code 18.8.2.3
requires that the column dimension parallel to the beam
reinforcement must be at least 20 times the diameter of the
largest longitudinal bar.
ACI Provisions for Special Moment Resisting Frames (SMRF)
Beam longitudinal reinforcement with diameter (db)
20db
Beam
Column
78
![Page 40: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/40.jpg)
40
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Joints of Special Moment Frame
Beam longitudinal reinforcement that is terminated within a
column. must be extended to the far face of the column core.
The development length (ldh) of bars with 90° hooks must be not
less than 8db, 6 inch, Or fydb/ (65 √ fc′).
The ACI 318-14 does not give complete details for the design
and detailing of joints of SMRF. For details see ACI 352-02
ACI Provisions for Special Moment Resisting Frames (SMRF)
79
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for Flexural Members
1. Size: No special requirement (Just as ordinary beam
requirement).
2. Flexural steel: Less stringent requirement as discussed next.
3. Transverse steel: Same as for SMRF.
4. Lap: No special requirement (Just as ordinary beam
requirement).
ACI Provisions for Intermediate Moment Resisting Frames (IMRF)
80
![Page 41: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/41.jpg)
41
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provisions for Flexural Members
2. Flexural Reinforcement
ACI Provisions for Intermediate Moment Resisting Frames (IMRF)
Asl−
Asl+ (Asl−)/3
As− or As+ (at all section) (maximum of As at either joint)/5
Asr−
Asr+ (Asr−)/3
rmin = 3f’c/fy, 200/fy (at critical sections)
t ≥ 0.004
81
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for Columns
1. Size: No special requirement (Just as ordinary column
requirement)
2. Flexural steel: No special requirement (Just as ordinary column
requirement)
3. Transverse steel: Less Stringent requirement as given next.
4. Lap: No special requirement (Just as ordinary column
requirement)
ACI Provisions for Intermediate Moment Resisting Frames (IMRF)
82
![Page 42: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/42.jpg)
42
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Provision for Columns
ACI Provisions for Intermediate Moment Resisting Frames (IMRF)
h2
h1
so/2
Trans. reinf. based on Mn and factored tributary gravity load
so
8 smallest long. bar dia.
24 tie bar dia.
0.5 min. (h1 or h2)
12”
lo
lo
Larger of h1 or h2
Clear span/6
18”
s ≤ d/2 (As per ACI 25.7)
83
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
IMRF are not allowed in regions of high seismic risk, however,
SMRF are allowed in regions of moderate seismic risk.
Unlike regions of high seismic risk, two way slab system without
beams are allowed in regions of moderate seismic risk.
In regions of low or no seismic risk ordinary moment resisting
frames OMRF are allowed but IMRF and SMRF may also be
provided.
Miscellaneous Considerations
84
![Page 43: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/43.jpg)
43
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Detail the selected frame of E-W interior frame of the given
structure as per SMRF requirements. The structure is already
designed for the following seismic zone data.
Seismic zone: 4
Magnitude of earthquake ≥ 7.0
Slip rate ≥ 5.0
Closest distance to known seismic source > 15 km.
Soil type: SD (stiff).
Concrete compressive strength = 3 ksi,
Steel yield strength = 40 ksi
Modulus of elasticity of concrete = 3000 ksi.
Design Example
85
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Given 3D structure:
Design Example
20 ft 20 ft 20 ft 20 ft
15 ft
15 ft
15 ft
10.5 ft
10.5 ft
10.5 ft (floor to floor)
SDL = 40 psfLL = 60 psf
SDL = 40 psfLL = 60 psf
SDL = 40 psfLL = 60 psf
fc′ = 3 ksify = 40 ksi
Zone = 4Ca = 0.44Cv = 0.64
I = 1W = 2002
V = 259 kip
Slab-Beam Frame
Structure
Beams: 15″ × 24″Columns: 15″ square
86
![Page 44: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/44.jpg)
44
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Load Combinations
ACI 318-14 load combinations have been used.
1.2D+ 1.6L
1.2D + 1.0L + 1.0E
1.2D + 1.0L − 1.0E
0.9D + 1.0E
0.9D − 1.0E
Design Example
87
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
Analysis
Analysis has been done using SAP2000. SAP2000 develops
envelop of maximum bending moments automatically for the
given load combinations.
88
![Page 45: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/45.jpg)
45
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
Analysis
Analysis results for shown portion of E-W interior frame is
shown next.
20 ft 20 ft 20 ft 20 ft
15 ft
15 ft
15 ft
10.5 ft
10.5 ft
10.5 ft (floor to floor)
89
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Analysis Results
90
E
-37 -37
26
-13.6 -13.6
11
-0.5
1.0
-1.4
2.0
-38.7
-38.7-72
67
-68
61
1.0D 1.0L 1.0E −1.0E
72
-67
68
-61
-38.7
38.7
1.2D + 1.6L
-80 -80
49
-2.5
4
1.2D + 1.0L + 1.0E
-19.3 -96.7
42
-74
70
-70
64
1.2D + 1.0L − 1.0E
-96.7 -19.3
42
70
-64
67
-58
0.9D + 1.0E
+4-82
23
-73
69
-69
63
0.9D − 1.0E
-82+423
70
-65
68
-59
-96.7 -96.7+49
-74 -70
Envelop
70 64
+4 +4
E
Bent left (+) Bent right (−)
BM Sign convention for column
Bent down (+) Bent up (−)
BM Sign convention for beam
Design Example
![Page 46: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/46.jpg)
46
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
Selected portion of E-W interior Frame:
Bending Moment Envelop
As the software checks SMRF moment capacity requirements and ACI
minimum moment capacity requirements at critical sections. Therefore
final shape of the bending moment envelop of the beam is as shown:
20 ft 20 ft 20 ft 20 ft
95.3
−96.7 −96.7
48.3 48.3 Values used in design-96.7 -96.7
+49-74 -74
Analysis Envelop
70 64
+4 +4
91
According to SMRF requirements the +ve As at the beam ends = ½ -ve As at beam ends. Therefore value of 4 has been changed to 48.3. Mid span bending moment value of 49 has been changed to 95.3 due to the requirement of minimum reinforcement at critical regions.
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Reinforcement from Design:
20 ft 20 ft 20 ft 20 ft
1.61 1.61
1.02 1.021.57
2.25 2.25
Reinforcement in in2
Design Example 2 (SMRF)
92
For the beam in the given frame, we have
Asmin = 0.005 x15 x 21 = 1.575 in2
Asmax = 0.025x15 x 21 = 7.875 in2
Negative reinforcement at the ends and
positive reinforcement at the mid span must
be greater than Asmin and reinforcement at all
locations must be less than the Asmax
This is OK for the values on the given beam.
For the column, we have
Asmin = 0.01 x15 x 15 = 2.25 in2
This is also OK.
![Page 47: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/47.jpg)
47
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
Calculation of number of bars:
20 ft 20 ft 20 ft 20 ft
# of bars = As/Ab
Use No. 5 bar,
Negative reinforcement at beam ends:
Left end:
1.61/0.31= 5.19 (take 6 bars in 2 layers)
Right end:
1.61/0.31= 5.19 (take 6 bars in 2 layers)
Positive bars (mid span):
1.57/0.31 = 5.1 (take 6 bars in 1 layer)
Positive bars (at joint):
1.01/0.31 = 3.29 (take 4 bars in 1 layer)
Column reinforcement:
2.25/ 0.31 = 7.25 (take 8 bars for even
distribution of bars at all faces of column)
6 bars 6 bars
4 bars 4 bars6 bars
8 bars 8 bars
No. of #5 bars
93
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
SMRF Requirements Checklist
Provisions for Beams
Sizes
ln/d = 20 × 12/21 = 11.4 > 4 (ACI 18.6.2.1a satisfied)
Width/ depth = 15/24 = 0.625 > 0.3 (ACI 18.6.2.1b satisfied)
Width = 15″ > 10″, O.K.
Therefore 15″ × 24″ deep beams is OK.
94
Design Example
![Page 48: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/48.jpg)
48
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
SMRF Requirements Checklist
Provisions for Beams
Flexural Reinforcement
95
Design Example
As+ (at joints) ≥ ½ As− (at joints)
4 #5 bars ≥ ½ (6 #5 bars)
As (any section) ≥ ¼ Max. As at joints
2 #5 bars ≥ ¼ (6 #5 bars)
As (at all critical sections) ≥ Asmin
As Asmin = 6 #5 bars
As (at any section) ≤ Asmax
Asmax = 0.025bd = 25 #5 bars
OK
OK
Provide at least 6 bars at critical sections)
OK
Asl− = 6 #5 Asr− = 6 #5
Asmid+ = 6 #5Asl+ = 4 #5 Asr+ = 4 #5
OK
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
SMRF Requirements Checklist
Provisions for Beams
Flexural Reinforcement
96
Design Example
Asl− = 6 #5 Asr− = 6 #5
Asmid+ = 6 #5Asl+ = 4 #5 Asr+ = 4 #5
![Page 49: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/49.jpg)
49
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
SMRF Requirements Checklist
Provisions for Beams
Transverse Reinforcement
97
Design Example
s
d/4 = 21/4 = 5.25″
8 smallest long. bar dia.= 8 × 5/8= 5″
24 hoop bar diameter = 24 × 3/8= 9″
12” 2”
2h = 48″s d/2 = 21/2 = 11″
Column
2h = 48″
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
SMRF Requirements Checklist
Provisions for Beams
Lap Splice: If required then,
Not to be provided within joints. Not to be provided within 2h region from face of
the support.
Spacing of hoops within lap = least of d/4 or 4″ c/c = 4″ c/c
Lap splice length =1.3 ld = 1.30.05 (fy/ √fc′)db ≈ 30″ = 2.5′
50 db = 50 (5/8) = 31.25″ ≈ 2.5′ for fc′ 3 and fy 40 ksi
98
Design Example
2h=48″ 2h=48″
![Page 50: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/50.jpg)
50
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
SMRF Requirements Checklist
Provisions for Columns
Size: All columns are 15″ square, which is more than least required for
SMRF (i.e., 12″).
Flexural Reinforcement: All columns are reinforced with 8 #5 bars
which gives ρg = 0.011, within the specified range 0.01 ≤ ρg ≤ 0.06.
99
Design Example
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
SMRF Requirements
Checklist
Provision for Columns
Transverse Reinforcement:
lo = max (larger column
dimension, hc/6, 18″) = 18″
Spacing of ties in lo region is
least of = smaller column
dimension/4, 6 long bar
dia = 3.75″
Spacing in the remaining
region will be least of 6
long bar dia or 6″ = 3.75″
hc = 8.5′
lo
lo
15” × 15” column
8, #5 bars
100
![Page 51: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/51.jpg)
51
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
SMRF Requirements Checklist
Provisions for Columns
Lap Splice:
Tension lap splice within center
half of member length.
Spacing of ties in lap splice not
more than smaller of d/4 or 4″
Lap length = 1.3 0.05 (fy/ √fc′ )db=
30″ ≈ 2.5′
And from 50db = 50(5/8) =
31.25″
hc = 8.5′
101
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
SMRF Requirements Checklist
Provision for Joints
To prevent beam column joint cracking, ACI Code 18.8.2.3 requires that
the column dimension parallel to the beam reinforcement must be at
least 20 times the diameter of the largest longitudinal bar.
20 × 5/8 = 12.5″
Column dimension parallel to beam long bar = 15″, OK
102
![Page 52: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/52.jpg)
52
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
SMRF Requirements Checklist
Provision for Joints
6 #5 bars
6 #5 bars
2″
ColumnBeam
Joint
Interior joint
103
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
SMRF Requirements Checklist
Provision for Joints
For exterior columns, the column dimension parallel to beam longitudinal
bar must be greater than the development length of beam bars in
columns with 90° hooks is not to be less than largest of:
The development length of beam bars in columns with 90° hooks is not
to be less than largest of:
8db = 8 × 5/8 = 5″
6″
ldh = fydb/(65 √fc′) = 40000 × (5/8)/ {65 × √(3000)} = 7″
Therefore, development length = 7″. The column dimension is 15″ which
satisfies this requirement.
104
![Page 53: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/53.jpg)
53
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
Design Example
SMRF Requirements Checklist
Provision for Joints
2″
Development of beam reinforcement in column = 13″ > ldh = 7″
Development of beam reinforcement in column = 22″ > ldh = 7″
ColumnBeam
Joint
Exterior Joint
105
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
References ACI 318-14
Design of Concrete Structures by Nilson, Darwin and Dolan.
UBC-97
BCP
106
![Page 54: Introduction to Earthquake Resistant Analysis & Design …drqaisarali.com/upload/lectures/Lecture 10_Introduction...3 Department of Civil Engineering, University of Engineering and](https://reader031.vdocument.in/reader031/viewer/2022022511/5ae179fc7f8b9ab4688ebba5/html5/thumbnails/54.jpg)
54
Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan
Prof. Dr. Qaisar Ali CE 5115 Advance Design of Reinforced Concrete Structures
The End
107