se apprentice lecture 1 final.ppt -...

10/13/2015

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SE APPRENTICELecture One – Loads

Today’s Speakers

Today’s Moderators

Lisa Willard, PESE Solutions, LLC

Brian Quinn, PESE Solutions, LLC

Carrie Bremer, PESchaefer

Stephen Metz, PESMBH, Inc.

SE Apprentice Content Created by Carrie Bremer & Stephen Metz; Event produced by SE Solutions, LLC

Company Overview

We are:

� Open-minded in our

approach + thinking

� Approachable thought leaders WITH diverse

experience

� Tirelessly collaborative

� Devoted to accuracy

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Who We Are

Carrie Bremer, PE� 11 Years Experience

� Works on a variety of project types

including, renovations, new

construction, investigations

� Experience in all material types including steel, concrete, wood &

masonry

� Active in the Structural Community

� SEAoO Basic Education Committee & Ohio State University Student Chapter Advisor

� NCSEA Basic Education Committee4

Company Overview

� Established in 1972

� Staff of 35

� Work across the country and internationally

� Work on all building types and structural systems

� Collaborative approach to projects

� Industry thought leader

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Who We Are

Stephen Metz PE, LEED AP

� President

� 21 Years Experience

� Experience includes large complex projects,

small simple projects, international work, peer reviews and expert witness

investigations

� Numerous speaking engagements and published articles on industry topics

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Course Goals and Overview

� The main goal is to introduce and discuss

aspects of building structural design that are not covered in the curriculum

� Four Lectures

1. Loads: What Are They and Where Do They Come From?

2. Systems and Paths

3. Design and Coordination

4. Contract Documents

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The Project

South Central Chiller Plant Generator Building

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What SE’s Do

� Design building structures

� Work with architects and other engineers (MEP, Civil, Geotechnical)

� Work with contractors and construction

managers

� Work with owners

� Protect the public

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The Structure

What is the purpose of

The Building Structure???

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Rules of Structural Engineering

� “It is time that we quit seeing ourselves as merely designing beams and columns, and start recognizing and proclaiming that we save lives for a living”Barry Arnold PE, SE

“What do you do for a living?”, Structure Magazine Sept 2009

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� “Structural Engineering is the Art of moulding materials we do not wholly understand into shapes we cannot precisely analyse, so as to withstand forces we cannot really assess, in such a way that the community at large has no reason to suspect the extent of our ignorance”Dr. A. R. Dykes & Dr. E. H. Brown

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� All dead and live loads end in 0 or 5

� There are no decimal places on numbers bigger than 10 (i.e. 354.87 kips ??)

� 102% of allowable is 100%

� Deflection controls most of the time

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Codes

� Model Codes

� International Building

Code 2009

� Governing Code

� Ohio Building Code 2011

� Reference Standards

� ASCE 7-05

� AISC 360-05 (Steel

Manual 14th Ed, Part 16)

� ACI 318-08

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ASCE 7 Loads

�Dead Load

�Soil & Hydrostatic Pressure

�Live Load

�Flood

�Snow

�Rain

�Ice

�Seismic

�Wind

Occupancy Categories

Occupancy

Category

Nature of Occupancy

I LOW hazard to human life in event of failure

Examples: Agricultural, Temporary & Minor Storage Facilities

II Those NOT listed in Occupancy Categories I, III or IV

Examples: Office, Retail & Commercial Buildings

III SUBSTANTIAL hazard to human life in event of failure

Examples: Schools, Jails, Buildings with Public Assembly Areas containing

greater than 300 occupants

IV Designated as an ESSENTIAL facility

Examples: Hospitals, Police, Fire & Rescue Stations, Designated Emergency

Shelters, Critical National Defense Facilities

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Importance Factors

Occupancy

Category

Importance Factors

Wind, Iw Snow, Is Seismic, IE

I 0.87 0.80 1.00

II 1.00 1.00 1.00

III 1.00 1.10 1.25

IV 1.15 1.20 1.50

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Floor Live Loads

Live Loads- The weight of People and all of their “Stuff”

ASCE 7 Definition

Live Loads – those loads produced by the use and occupancy of the building or other structure and do not include construction or environmental load such as wind load, snow load, rain load, earthquake load, flood load or dead load.

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Floor Live Loads

Floor Live Loads* (Table 4-1)Assembly- 100 psf Parking Garages- 40 psf

Dining Restaurant- 100 psf Classroom- 40 psf

Light Storage- 125 psf Heavy Storage- 250 psf

Residential- 40 psf First Floor Retail- 100 psf

Stairs- 100 psf Balconies- 100 psf

Offices- 50 psf Terraces- 100 psf

Office Corridors- 80 psf

*Note that these are minimum requirements

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Floor Live Loads

8.75 sq ft

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Floor Live Loads

Live Load Reduction(Table 4-1)

The code recognizes that the probability of a floor being loaded to its full design live load is less likely as the area of floor that is being supported (tributary area) increases.

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Floor Live Loads

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Snow & Roof Live Load

� Roof Live Load

Occupancy or Use Uniform psf

Ordinary flat, pitched, and curved roofs 20

Roofs used for promenade purposes 60

Roofs used for roof gardens or assembly

purposes

100

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� How do we determine the forces applied to a

building due to snow loads?

� Location

� Building Use

� Occupancy Category

� Building Properties

� Roof geometry and shape

� Insulation values

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�Snow Load�Flat roof snow load

pf = pg .7Ce Ct I

but not less than

= pg Ipf25 pg = Ground Snow Load

pf =pg .7Ce Ct I

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.7Ce = Exposure Factor

pf = pg .7Ce Ct I

27 Ct = Thermal Factor

pf =pg .7Ce Ct I

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I = Importance Factor

pf = pg .7Ce Ct I

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pf = pg .7Ce Ct I

but not less than

= pg Ipf

Lr = 20 psf

=20x.7x1.0x1.0x1.2 = 17psf

= 20x1.2 = 24psf 25psf

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Unbalanced & Drifted Snow

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Wind Loads


building due to wind loads?

� Location

� Building Use


� Building Properties

� Building and Roof Geometry & Shape

� Height

� Ratio of openings (doors & windows) to closed area

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Location, Use & Height

�Velocity Pressure

qz = .00256 Kz Kzt Kd V2 I

33 Basic Wind Speed


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Velocity Pressure Exposure Coefficient


Topographic Factor


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� Directionality Factor


Kd = .85(most of the time)

37 Importance Factor


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Building Properties

� Main Wind Force Resisting System (MWFRS)

� p = q GCp –qi(GCpi)

� Components & Cladding (C&C)

� p = qh [(GCp) –(GCpi)]

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Wind Loads

� Windward & Leeward Forces

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Wind Loads

� Sidewall

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Wind Loads

� Uplift Forces

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Wind Loads

� Internal Pressure Coefficient

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Wind Loads

� Velocity pressure @ h = 26 ft

�qz = .00256 Kz Kzt Kd V2 I

�qz = .00256x.95x1.0x.85x902x1.15 = 19 psf

� MWFRS pressure @ h = 26 ft

�p = q GCp + qi(GCpi)

�p = 19x.85x.8 - 19x-0.18 = 16psf WW_ 19x.85x-.5 - 19x-0.18 = -5psf LW

21 psf

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Dead load

Dead Loads- The weight of all components of

the Architecture and Structure

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Dead Load

� Membrane – 2psf

� Insulation – 2 psf

� Deck – 2 psf

� Beams/joists – 7 psf

� Mechanical – 5psf

� Miscellaneous – 2psf

Typical Roof Dead Load Generator Roof Dead Load

20 psf

� Membrane – 2psf

� Insulation – 2 psf

� Deck – 3 psf

� Beams/joists – 8 psf

� Mechanical – 35psf

� Miscellaneous – 3psf

55 psf

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� Row Houses by 3 Little Pigs Construction Co.

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Seismic Loads


building due to seismic loads?

� Location

� Soil Properties

� Building Properties and Use

� Weight

� Height & Stiffness


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Base Shear

� Equivalent Lateral Force Procedure

V= Cs W

Cs = SDS

(R/I)

Cs = SD1

T(R/I)For T< TL

But need not be more than

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Location & Soil Properties

�Design Spectral Acceleration Parameters

SDS = 2/3 Fa Ss

SD1 = 2/3 Fv S1

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Maximum Considered Earthquake (MCE) Ground Motion at short periods

SDS = 2/3 Fa Ss

Maximum Considered Earthquake (MCE) Ground Motion at a 1 second period

SD1 = 2/3 Fv S1

Location & Soil Properties

�Site Class SDS = 2/3 Fa Ss

SD1 = 2/3 Fv S1

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Seismic Design Category

� Combines location, soil & occupancy

parameters

Occupancy Category

SDS SD1 I or II III IV

SDS < 0.167g SD1< 0.067g A A A

0.167g<SDS<0.33g 0.067g<SD1<0.133g B B C

0.33g<SDS<0.50g 0.1.33g<SD1<0.20g C C D

0.50g<SDS 0.20g<SD1 D D D

MCE, S1>0.75g E E F

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� Lateral system selection

� Special Detailing

� Other Special Requirements

� Bracing architectural and mechanical components

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� Lateral system selection

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Approximate Fundamental Period

�Ta = Ct hxn

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Base Shear

� Equivalent Lateral Force Procedure

V= Cs W

Cs = SDS

(R/I)

Cs = .068

.22(3/1.5)

Cs = .12

(3/1.5)

= 0.06

Cs = SD1

T(R/I)For T< TL

= 0.152

V= 0.06x396k = 24k59

Vertical Distribution

� Lateral Seismic Force (story force)

Fx = Cvx V

Cvx = wx hxk

wi hik∑

n

i=1

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Vertical Distribution

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Loads on Generator

� Live

� 100 psf

� Snow

� 25 psf

� Wind

� 21 psf MWFRS

� -19 psf C&C (wall zone 5, A = 358ft2)

� Base Shear

� 24k

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Carrie Bremer [email protected]

614.706.5405

www.schaefer-inc.com

Stephen Metz [email protected]

614.481.9800

www.smbhinc.com

Questions?

Which Code mentioned during today’s session is the answer to the challenge question?

• International Building Code 2009

• ASCE 7-05

• AISC 360-05

• ACI 318-08