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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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Rules of Structural Engineering
� “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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Rules of Structural Engineering
� 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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Snow & Roof Live Load
� 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 & Roof Live Load
�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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Snow & Roof Live Load
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
� How do we determine the forces applied to a
building due to wind loads?
� Location
� Building Use
� Occupancy Category
� 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
qz = .00256 Kz Kzt Kd V2 I
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Velocity Pressure Exposure Coefficient
qz = .00256 Kz Kzt Kd V2 I
Topographic Factor
qz = .00256 Kz Kzt Kd V2 I
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� Directionality Factor
qz = .00256 Kz Kzt Kd V2 I
Kd = .85(most of the time)
37 Importance Factor
qz = .00256 Kz Kzt Kd V2 I
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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
� How do we determine the forces applied to a
building due to seismic loads?
� Location
� Soil Properties
� Building Properties and Use
� Weight
� Height & Stiffness
� Occupancy Category
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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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Seismic Design Category
� Lateral system selection
� Special Detailing
� Other Special Requirements
� Bracing architectural and mechanical components
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Seismic Design Category
� 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