Lecture 01
High-Rise Steel Buildings
Prepared By:
Dr. M. Hassanien Serror
Lecture 01
Contents
Chapter 1: Loads
1.1 – Vertical (Gravity) Loads (Rain, Snow, Dead, and Live)
1.2- Lateral Loads (Wind, and Seismic)
Chapter 2: Systems
2.1 Lateral Load System
2.2 Gravity Load System (Floor Beams & Columns)
Chapter 2: Analysis
2.1 FEM Review
2.2 High-Rise Steel Bldg FEM Analysis
Chapter 2: Design
2.1 Elements Design
2.2 Connections Design
Lecture 01
http://www.egypteducation.org/moodle/
Enrollment Key: highrisesteel
Lecture 02
High-Rise Steel Buildings
Prepared By:
Dr. M. Hassanien Serror
Lecture 02
Chapter 1: Loads
1.1 – Vertical (Gravity) Loads
Rain, Snow, Dead, and Live
1.2- Lateral Loads
Wind, and Seismic
Lecture 02
Lecture 02
1.1 Vertical (Gravity) Loads
Within the course, we shall consider only two
types of Gravity Loads:
1- Dead Loads, and
2- Live Loads
Dead Load:
Floor Beams/Joists = 100 Kg/m2
Metal Deck + R.C. Slab = 300 Kg/m2
Flooring = 150 Kg/m2
Partitions = 150 Kg/m2
Mechanical/Piping = 100 Kg/m2 800Kg/m2
Lecture 02
Lecture 02
Live Load:
According to Egyptian Code of Practice
- Residential (200~300 Kg/m2)
- Administration (250~400 Kg/m2) P
- Storage (500~1000 Kg/m2)
- Halls/Conf. Rooms (400~500 Kg/m2)
- Shopping Malls (500 Kg/m2)
- Hotels (200~400 Kg/m2)
- Library (300 Kg/m2)
- Cinema (400~600 Kg/m2)
- Garage (300 Kg/m2)
Lecture 02
Live Load Reduction: P
P
For For
ONLY:
ONLY: P
- Residential Floors,
Residential andand
Floors, P
- Multi-Storey Bldgs > 5 stories P
0.9P
For ONLY: 0.8P
- Walls/Columns Design, and 0.7P
0.6P
- Foundation Design
0.5P
0.5P
0.5P
0.5P
0.5P
0.5P
Lecture 02
Gravity Load Flow:
Floor Beams/Joists Girders Columns
Lecture 02
Gravity Load on Floor Beams/Joists:
Lecture 02
Gravity Load on Girders:
Lecture 02
Gravity Load on Columns:
Lecture 02
Gravity Load Share:
Lecture 02
Lecture 03
High--Rise Steel Buildings
High
Prepared By:
Dr. M. Hassanien Serror
Lecture-03
Chapter
p 1: Loads
1 1 – Vertical (Gravity) Loads
1.1
Rain,, Snow,, Dead,, and Live
1.2- Lateral Loads
Wind, and Seismic
Lecture-03
1.2 Lateral Loads (Wind Load)
¾ Difference Between Vertical and Lateral Loads:
Lecture-03
¾Lateral Load Flow
Lecture-03
¾ Wind Load Characteristics
1. Variation of Wind Velocity with Height.
2 Turbulent
2. T b l Nature
N off Wind.
Wi d
3. Probabilistic Approach.
4. Vortex Shedding Phenomena.
5. Dynamic nature of Wind-Structure interaction.
Lecture-03
1. Variation of Wind Velocity with Height.
α
⎛ Z ⎞
Vz = Vg ⎜
⎜Z ⎟
⎝ g⎠
Vz = Mean Wind Velocity @ Height Z
Vg = Gradient Velocity
Z g = Gradient Height
Z = Height above Ground
α = Power - Law Coefficient
Lecture-03
2. Turbulent Nature of Wind
M h d1
Method
Vt = V + v′
V = Mean Wind Velocity
v′ = Instantanous Velocity Fluctuation about V
Method 2
Vg = GVV
Vg = Gust Velocity
GV = Gust Factor From Wind Tunnel Test (Dyn. characteristics)
V = Mean Wind Velocity
Turbulence Æ Dynamic Effect Æ More Pressure
Lecture-03
3. Probabilistic Approach.
- Average Wind Velocity in 50-Year means Prob.
Of Occurrence 1/50
/ = 2%
- i.e., Prob. To exceed the average velocity is 2%
- Return Period = Recurrence Interval
Lecture-03
4. Vortex Shedding Phenomenon.
Laminar Wind Flow
Turbulent Wind Flow
Lecture-03
5. Dynamic Nature of Wind Structure Interaction
1. Time Dependent Velocity and Pressure
2 Natural frequency of Structure and Frequencies of Wind
2.
Lecture-03
¾ Wind Load in Codes
1. Egyptian Code for Loads (2003).
2 Egyptian
2. E i C Code
d ffor L
Loads
d (2008
(2008-Draft)
D f)
3. Uniform Building Code (UBC).
4. American National Standards Institute (ANSI).
5. Standard Building Code (SBC).
6. National Building Code of Canada (NBC).
Lecture-03
1. Egyptian Code for Loads (2003)
P = Ce kq
Ce = External Pressure Coefficient (geometry - dependent)
k = Exposure - with - height Coefficient 1.0~2.3
q = Basic Wind Pressure (location - dependent) 50~90 kg/m2
g
120~140 km/hr
Lecture-03
1. Egyptian Code for Loads (2003)
¾ Egyptian Code 2003 is not Applicable for Buildings:
1. Height > 60m
2 Height > 4-times of smaller dimension in plan
2.
3. Irregular shapes
4. In abnormal locations
Lecture-03
1. Egyptian Code
for Loads
(2003)
Lecture-03
2. Egyptian Code for Loads (2008 - Draft)
P = Ce kq
q
Ce = External Pressure Coefficien t (geometry - dependent)
k = Exposure
p g Coefficien t 1~2.5
- with - height .5
q = Basic Wind Pressure (location - dependent) 57~110 kg/m2
N/m2 /
110~150 km/hr
Lecture-03
118 km/hr
Lecture-03
Egyptian Code 2008 is not
Applicable for Buildings
of irregular/abnormal
shapes. Lecture-03
3. Uniform Building Code
P = CeCq Iq
I s
Ce = Combines effect of Height, Exposure, and Gust
Cq = Depends on Structural Lateral System
I = Importance Factor, 1.15 for essential buildings
qs = Wind Pressure at H = 33ft (10m) for 50 years return period
UBC Code refers to ANSI Code for High Rise
Buildings.
Lecture-03
4. American National Standards Institute (ANSI)
1. Define Structure Category
• Category (I): All Buildings except those mentioned
below.
• Category (II): Bldgs & Str where primary
occupancy
p y >300 people.
p p
• Category (III): Hospitals, Fire Brigade, Police
Stations etc.
Stations, etc (essential buildings).
buildings)
• Category (IV): Low Hazard to Human Life in
event of failure.
Lecture-03
2. Define Importance Factor
• Category (I) Æ 1.0
• Category (II) Æ 1.07
1 07
• Category (III) Æ 1.07
• Category (IV) Æ 0.95
3. Select Basic Wind Velocity
• Average
A Wi
Wind
dVVelocity
l i iin 50
50-Years
Y R
Return P
Period.
i d
4 Determine H/B Ratio
4.
H=Bldg Height B=Bldg Smallest Dim. in plan
H/B ≤ 5 Æ Rigid Str., H/B>5 Æ Flex. Str.
Lecture-03
5. Define Bldg Exposure
• Exposure A
• Exposure B
• Exposure C
• Exposure D
Lecture-03
6. Determine Exposure Constants (α. D0, Zg)
α
⎛ Z ⎞
Vz = Vg ⎜ ⎟
⎜Z ⎟
⎝ g⎠
Vz = Mean
M Wi d Velocity
Wind V l it @ Height
H i ht Z
V = Basic Wind Velocity
Z g = Gradient Height
Z = Height above Ground
α = Power - Law Coefficient
Lecture-03
7. Determine Gust Factor
If H/B ≤ 5 (Rigid Str.)
Str )
G = 0.65 + 3.65TZ
2.35(D0 )
0 .5
TZ = 1
⎛ Z ⎞α
⎜ ⎟
⎝ 30 ⎠
G = Gust Factor to account for Turbulane
Z = Variable Height in ft.
If H/B > 5 (Flex. Str.)
⎡ p (3.32T1 )2 S ⎤
0.5
G = 0.65 + ⎢ + ⎥
⎣ β 1 + 0. 0002C ⎦
β = Damping Coefficient (0.02)
T1 = Exposure Factor at 2/3H
S,C = From Tables based on Exposure Category
p = Pressure Factor based on Frequency
Lecture-03
8. Determine Velocity Pressure qz
qz = 0.0025K z (IV )
2
qz in psf,
i mphh
V in
K Z = Velocity Pressure Coefficient Exposure
9. Determine External Pressure Coefficient Cp
• Based on Wind and face Direction.
10. Determine Wind Pressure P
P = C pGqZ
Lecture-03
Sheet‐1:
For the previous example, recalculate the force F1
using ASCE‐7‐02 Code for Wind Load
Lecture-03
Lecture 04
High-Rise Steel Buildings
Prepared By:
Dr. M. Hassanien Serror
Lecture-04
Solving Wind Load Example
Calculate F1 due to Windward and Leeward
Wind Load
Lecture-04
American National Standards Institute (ANSI)
1. Define Structure Category III
2. Define Importance Factor 1,07
3. Select Basic Wind Velocity 70-mph
4. Determine H/B Ratio 60/15=4<5 (Rigid Str.)
5. Define Structure Exposure D
6. Determine Exposure Constants (α. Zg , D0 )
For Exposure D:
α = 10.0, Zg = 700-ft, and D0 = 0.003
Power-Law Factor
Gradient Height
Surface Coefficient Factor
Lecture-04
7. Determine Velocity Pressure qz
For Exposure D and Height Z=(60/0.3048)=196.85-ft:
Velocity Pressure Exposure Coefficient KZ
= 2.58(196.85/700)0.2 = (2.0)
2
qz = 0.0025K z (IV )
2
qz = 0.0025 * 2.0 * (1.07 * 70) = 28.05 - psf
8. Determine Gust Factor
H/B ≤ 5 (Rigid Str.)
0.5
2.35(D0 )
TZ = 1
= 0.1066 Exposure Factor at Mean Roof Height
Z α
30
G = 0.65 + 3.65TZ = 1.04 Gust Factor
Lecture-04
9. Determine External Pressure Coefficient Cp
CP=-0.7
L/B ≤ 1 CP = 0.8
CP=-0.7
CP=-0.7 B CP=-0.2
CP=0.8
L
CP=0.8 B C =-0.5
P
L CP=0.8 B CP=-0.3 CP=-0.7
L
L/B =4
CP=-0.7
L/B ≤1 CP=-0.7
L/B =2
10. Determine Wind Pressure P E.C.P.
PZ =60 m = C p G qZ = 23.33 - psf (114 kg/m2) (0.8x1.7x90) 122 Kg/m2
PZ =45m = C p G qZ = 22.27 - psf (109 kg/m2) (0.8x1.5x90) 108 Kg/m2
F1(Wind Ward)=[((114+109)/2)*(15/2)*15]/1000=12.5-ton
Lecture-04
1.1 – Vertical (Gravity) Loads
Rain, Snow, Dead, and Live
1.2- Lateral Loads
Wind, and Seismic
Lecture-04
Seismic Load Introduction
Earthquake Nature
Earthquake Intensity Scale
Tall Buildings Concerns
Seismic Load Calculations (Brief)
What may happen during an Earthquake?
Earthquake Research Countermeasures
Lecture-04
Earthquake Nature
Eurasian Plate Tokyo
Kobe
Co Pacific Plate
nt
in
en
ta
lc
ru
st Philippine
Sea Plate
Oc
ean
i cc
rus
t
Lecture-04
Earthquake Nature
Lecture-04
Earthquake Intensity Scale
Richter Scale - Amount of energy released.
- Wave amplitude & epicenter distance.
-Location independent.
Lecture-04
Earthquake Intensity Scale
Mercalli Scale - Actual effects at particular location.
- Location dependent.
Lecture-04
Tall Buildings Concerns
- Building Natural Frequency (Natural Period).
- Higher Modes of deformation.
- Resonance.
- Damping (Viscous, Hysteretic, Friction).
- Earthquake Frequency.
Viscous Hysteretic Friction
@ Bracing @ Material @ Joints Lecture-04
Equivalent Static Load
Egyptian Code of Practice:
Calculate Base Shear V: Dead load + L.L if L.L.<=500Kg/m2
V=ZIKSCW Dead load + 0.5 L.L if L.L.>500Kg/m2
Z: Seismic Zone (from seismic map: 1 0.1, 2 0.2, 30.3).
I: Importance Factor (1.25, 1.0).
K: Structural Lateral System Factor 1.33: shear walls or braced frames
0.67: steel frames
0.80: R.C. frames
1.00: shear walls and frames
S: Local Soil coefficient (Rock1.0, Medium1.15, Soft1.3)
C: a/g= 1 (15 T ) T = 0.1N Frame System
T = 0.09H B Other Systems
N: including basement floors, H: from Foundation, B: in direction of EQ
Lecture-04
Equivalent Static Load
Egyptian Code of Practice:
Load Distribution:
Ftop = 0.07 TV < 0.25V if T > 0.7 sec. Ftop
w7
= Zero if T<= 0.7 sec.
(V − Ftop ) wi hi F4
Fi =
∑wh i i
h4
w1
Fi : Force at Floor i
wi : Floor Weight
hi : Floor Height from Foundation
Disadvantages:
- Effect of higher modes, Conservative, and Force is linear with height
Lecture-04
What may happen during an Earthquake?
1995 Kobe Earthquake
When January 17, 1995, 5:46:52 a.m.
Richter magnitude 7.2
Epicenter 16 km depth
Tsunami None
Victims 6500
Economic US$100 billion
Lecture-04
Kobe Earthquake (N-S Record)
g = 981 [m/sec2]
Acc. [m/sec2]
Time [sec.]
Lecture-04
Collapse of Kobe
Bridge
Lecture-04
Collapse of Kobe Bridge
Lecture-04
Brittle Failure of RC Columns
Lecture-04
Joints Fracture
Lecture-04
Different Damage/Collapse for same structure
Lecture-04
E.Q. Disaster
Consequences
Lecture-04
Evacuation Shelters
Lecture-04
Tall Buildings
1995 1996
35 floors
Lecture-04
Kobe on 1999
!
Lecture-04
Earthquake
Countermeasures
E-Defense
Lecture-04
E-Defense
Shaking table tests of a full-scale four-storey frame-system
(Steel Building)
Lecture-04
E-Defense
Shaking table tests of a full-scale six-storey frame-system
(RC Building)
Lecture-04
DOSE Software Environment
Hazard GIS
Risk DOSE Model DOSE Model
Assessment GIS
Z Geotechnical +
DOSE Model Y Data
GIS to simulate
X at-site Hazard Inventory +
Risk Compiler
Communic.
DOSE Model
t y
b ili
Economic C
ra
pe L
Impact e ro Vulnerability UL W
DOSE Model I nt
DOSE Model S AA
T NN
Applications E
Mass Urban System
R
Vulnerability
Evacuation
In
Analysis
te
DOSE Model
r op
er
DOSE
ab
ili
CONTROL ROOM Z
ty
Traffic Y
X
Congestion
DOSE Model USM CAD
DOSE Model DOSE Model
People CAD
Z Geotechnical
Education Y
Data Data
DOSE Model X Inventory +
Inventory +
Compiler
Compiler
Lecture-04
Full Scale Bridge Piers
Lecture-04
Full Scale City Buildings
Lecture-04
References:
- E-Defense @ Japan
http://www.bosai.go.jp/hyogo/ehyogo/index.html
- NEES @ US
http://www.nees.org/
Lecture-04
Lecture 05
High-Rise Steel Buildings
Prepared By:
Dr. M. Hassanien Serror
Lecture-05
Seismic Load Calculations
Structural Dynamics Review
Egyptian Code 1993
Egyptian Code 2003
Lecture-05
Structural Dynamics Review
Simplified Structure Modeling (SDOF):
ut = u + ug
k
ug m
cu& m c
ku k
m(u&& + u&&g )
Lecture-05
Structural Dynamics Review
Simplified Structure Modeling SDOF:
From Force Equilibrium: cu& m
m(u&& + u&&g ) + cu& + ku = 0 ku
mu&& + cu& + ku = −mu&&g m(u&& + u&&g )
c k
u&& + u& + u = −u&&g
m m
u&& + 2ξωu& + ω 2u = −u&&g Equation of Motion
2ξω = c m
2
ω =k m ω= k m
Lecture-05
Equation of Motion: &u& + 2ξωu& + ω 2u = −u&&g
Free Vibration:
u&& + 2ξωu& + ω 2u = 0
u&0 + ωξu0
sin(ωd t ) + u0 cos(ωd t )
−ξω t
u(t ) = e
ωd
ωd = ω 1 − ξ 2
Forced Vibration:
&u& + 2ξωu& + ω 2u = F (t )
Lecture-05
SDOF Demonstrations:
What is Natural Frequency ω= k m
What is Damping
c
ξ=
2ω m
What is Resonance ωg ≈ ω
Ground Motion ( u&&g ) Frequency (ωg) is close to SDOF System
Frequency (ω)
Lecture-05
Simplified Structure Modeling (MDOF):
Modal Analysis:
MDOF System consists of several SDOF Systems
m3 [M ]U&& + [C ]U& + [K ]U = −[M ]u&&g
u3
c3 k3 m2
u2 m1 0 0 c1 0 0
c2 k2 m1 0 m 0 0 c 0
u1 2 2
c1 k1 0 0 m3 0 0 c3
ug
mi u&&i + ci u&i + ki u = − mi u&&g k1 0 0
0 k 0
i = 1,2,3 2
ω1 , ω2 , ω3 0 0 k3
Lecture-05
MDOF Demonstrations:
MDOF System Mode Shapes? [M ]U&& + [K ]U = 0
([K ] − ω [M ]) {Φ} = {0}
2
Eigenvalue Problem
Det ([K ] − ω 2 [M ]) = 0 Solve for Mode Frequency ( ωi )
([K ] − ω [M ]){Φ } = {0}
i
2
i
Solve for Mode Shape ( Φi )
Lecture-05
Continuous System Modeling (Infinite Degrees of
Freedom IDOF):
Continuous System Mode Shapes?
Lecture-05
Seismic Load Representation:
1. Equivalent Static Method:
Proposed for Non-Flexible Structure
(High-Natural-Frequency/Low-Natural-Period)
Considering Fundamental Mode of Vibration only
Lecture-05
Equivalent Static Load
Egyptian Code of Practice:
Calculate Base Shear V: Dead load + L.L if L.L.<=500Kg/m2
V=ZIKSCW Dead load + 0.5 L.L if L.L.>500Kg/m2
Z: Seismic Zone (from seismic map: 1 0.1, 2 0.2, 30.3).
I: Importance Factor (1.25, 1.0).
K: Structural Lateral System Factor 1.33: shear walls or braced frames
0.67: steel frames
0.80: R.C. frames
1.00: shear walls and frames
S: Local Soil coefficient (Rock1.0, Medium1.15, Soft1.3)
C: a/g= 1 (15 T ) T = 0.1N Frame System
T = 0.09H B Other Systems
N: including basement floors, H: from Foundation, B: in direction of EQ
Lecture-05
Equivalent Static Load
Egyptian Code of Practice:
Load Distribution:
Ftop = 0.07 TV < 0.25V if T > 0.7 sec. Ftop
w7
= Zero if T<= 0.7 sec.
(V − Ftop ) wi hi F4
Fi =
∑wh i i
h4
w1
Fi : Force at Floor i
wi : Floor Weight
hi : Floor Height from Foundation
Disadvantages:
- Effect of higher modes, Conservative, and Force is linear with height
Lecture-05
Ex.-2
Lecture-05
