Homework: Seismic Design of Building Structures

Hannes Penninck 11/03/2015 Student ID: 1359308

BSM and Analysis Method

1. A 5-story reinforce concrete building is located at site of category III which design seismic

in group 1. The seismic zone of intensity for design is Ⅶ. After dynamic analysis for this

building, five modes and corresponding periods, participating factor are given and shown in

Figure 2. The damp ratio of this frame is 0.05.

1. Calculate the standard horizontal seismic actions at each story under frequent-occurring

earthquake by base shear method

Homework: Seismic Design of Building Structures

Hannes Penninck 11/03/2015 Student ID: 1359308

Homework: Seismic Design of Building Structures

Hannes Penninck 11/03/2015 Student ID: 1359308

Homework: Seismic Design of Building Structures

Hannes Penninck 11/03/2015 Student ID: 1359308

Homework: Seismic Design of Building Structures

Hannes Penninck 11/03/2015 Student ID: 1359308

2. Calculate the standard horizontal seismic actions at each story under frequent-occurring

earthquake by mode analysis method.

Homework: Seismic Design of Building Structures

Hannes Penninck 11/03/2015 Student ID: 1359308

Homework: Seismic Design of Building Structures

Hannes Penninck 11/03/2015 Student ID: 1359308

3. Compare two results and briefly introduce the effect of additional horizontal seismic action

applied at the top of the building in base shear method.

We can calculate the forces on each storage based on the 2 methods. The order of magnitude

is the same. But the BSM methods has lower forces at the base of the construction. The force

at the top of the construction is higher using BSM.

Floor BSM Analysis method

5 5,97 3,87

4 6,12 6,18

3 4,59 5,71

2 3,05 5,01

1 1,53 4,18

Explanation:

The BSM is a method who only uses the first mode. This mode has lower deformations at the bottom and higher deformations at the top. We had to add additional forces at the top in the BSM method. The reason for this is that the mode (1), is not dominant (Tg << T1). The other modes are more important.