Structural Review
Content
structure : review
dead load (DL)
permanent self weight including
structure, enclosure, finishes and
appendages.
live load (LL)
transitory loads based upon use and
occupancy including people,
automobiles and furniture.
snow load (S)
semi-permanent load based local
snowfall statistics. snow load may
have a lateral component.
Vertical Load Flow :
Tributary Area is the area that contributes load
to a specific structural element.
Tributary Width is the width of area that
contributes load to a specific element.
ω = (Trib Width) (Area Load)
PBM PBM PBM
PBEAM = (Trib Area) (Area Load)
PCOL
PCOL = (Trib Area) (Area Load)
Finding Internal Forces : Graphic Method
ω = 880 lb/ft
0 lb
20 ft
8.8 k
8.8 k
P
Alternatively use graphic method to construct
internal force (PVM) diagrams :
No Axial Load : Axial Diagram (P) = 0
Concentrated Jump at support of + 8.8 kips
Change in Shear diagram = Area of Loading
Area loading = - 880 lb/ft (20 ft) = - 17.6 kips
8.8 k
Another Concentrated Jump of +8.8 kips
V
10 ft
- 8.8 k
44 k-ft
No concentrated Moments… No jumps in Moment
Diagram
Change in Moment = Area of Shear Diagram
M
= 1/2 b h = 1/2 (8.8 k) (10 ft)
= 44 k-ft
Finding Internal Forces : Graphic Method
ω = 880 lb/ft
Mmax = 44 k-ft
0 lb
20 ft
8.8 k
8.8 k
Allowable Bending Stress :
P
Fb = 0.60 FY = 0.60 (50 ksi) = 30.0 ksi
Mmax = 44 k-ft (12 in / ft) = 528 k-in
8.8 k
fb = M/S
V
10 ft
- 8.8 k
44 k-ft
M
If using A992 Steel : FY = 50 ksi
Fb = Mmax / Srequired
SRequired = Mmax / Fb
SRequired = 528 k-in / 30.0 ksi = 17.6 in3
Finding Internal Forces : Graphic Method
ω = 880 lb/ft
Mmax = 44 k-ft
0 lb
20 ft
8.8 k
8.8 k
Allowable Bending Stress :
P
Fb = 0.60 FY = 0.60 (50 ksi) = 30.0 ksi
Mmax = 44 k-ft (12 in / ft) = 528 k-in
8.8 k
fb = M/S
V
10 ft
- 8.8 k
44 k-ft
M
If using A992 Steel : FY = 50 ksi
Fb = Mmax / Srequired
SRequired = Mmax / Fb
SRequired = 528 k-in / 30.0 ksi = 17.6 in3
USE W10x19, SX-X = 18.8 in3
Vertical Load Flow :
Tributary Area is the area that contributes load
to a specific structural element.
Tributary Strip is the width of area that
contributes load to a specific element.
spanning behavior and critical metric
L = 20 ft
If using wide flange steel
beam:
depth = L/18 = 1.11 ft = 13 in
(conservative)
W14 or W16 is a good
approximate size
L = 30 ft
If using flat reinforced
concrete slab:
depth = L/25 = 1.2 ft = 14.4 in
(conservative)
a 14 in thick slab is a good
approximate depth
column (compression strut) review
buckling shape
slenderness ratio = kl/r
L = unbraced length
compression and slenderness
slenderness ratio = kl/r
k = effective length coefficient
(boundary condition affect)
slenderness ratio = kl/r
r = radius of gyration
wood sections:
r = I/A
I = 1/12 b h3
slenderness ratio = kl/r
r = radius of gyration
steel sections - look up in table
range kl/r: 60-80 for columns
100-120 for trusses
r = radius of gyration
concrete sections:
r = 0.3 h (rectangular sections)
r = 0.25 h (circular sections)
slenderness ratio = kl/r
range kl/r: 40-60 columns
h (dia) = 12 in r = 0.3 h = 3.6 in
assume k = 1.0
l = 15’-0” = 180 in
kl/r = (1.0)(180 in) / 3.6 in
kl/r = 50
wind load (WL)
event lateral and uplift load caused by
windward and leeward wind pressure
(high mass helps resist overturning
and increases foundation friction)
earthquake load (EQ)
event lateral and vertical loads caused
by the acceleration of building mass
due to ground motion generated from
a fault rupture. (mass and height
increase lateral and vertical load)
3RD FLOOR LATERAL LOAD FLOW
STRUCTURAL SYSTEM
FORCE / Loads (ACTION)
MATERIAL : strength, stiffness, elasticity and ductility
CONFIRGURATION of components
ASSEMBLY : boundary conditions, joints (fixity), assembly hierarchy
CONFIRGURATION of assembly
FORCE FLOW (REACTION)
moment frame review
shear wall review
Long (Shear) Walls / Cores
(vertical cantilever)
surface/strut+tie action
L/d < 3
Tall (Flexural) Walls / Cores
(vertical cantilever)
bending action
L/d > 6
shear wall to core
tube systems
Swiss Re
diagrid tube systems
Architect : Norman Foster
dead load (DL)
permanent self weight including
structure, enclosure, finishes and
appendages.
live load (LL)
transitory loads based upon use and
occupancy including people,
automobiles and furniture.
snow load (S)
semi-permanent load based local
snowfall statistics. snow load may
have a lateral component.
Vertical Load Flow :
Tributary Area is the area that contributes load
to a specific structural element.
Tributary Width is the width of area that
contributes load to a specific element.
ω = (Trib Width) (Area Load)
PBM PBM PBM
PBEAM = (Trib Area) (Area Load)
PCOL
PCOL = (Trib Area) (Area Load)
Finding Internal Forces : Graphic Method
ω = 880 lb/ft
0 lb
20 ft
8.8 k
8.8 k
P
Alternatively use graphic method to construct
internal force (PVM) diagrams :
No Axial Load : Axial Diagram (P) = 0
Concentrated Jump at support of + 8.8 kips
Change in Shear diagram = Area of Loading
Area loading = - 880 lb/ft (20 ft) = - 17.6 kips
8.8 k
Another Concentrated Jump of +8.8 kips
V
10 ft
- 8.8 k
44 k-ft
No concentrated Moments… No jumps in Moment
Diagram
Change in Moment = Area of Shear Diagram
M
= 1/2 b h = 1/2 (8.8 k) (10 ft)
= 44 k-ft
Finding Internal Forces : Graphic Method
ω = 880 lb/ft
Mmax = 44 k-ft
0 lb
20 ft
8.8 k
8.8 k
Allowable Bending Stress :
P
Fb = 0.60 FY = 0.60 (50 ksi) = 30.0 ksi
Mmax = 44 k-ft (12 in / ft) = 528 k-in
8.8 k
fb = M/S
V
10 ft
- 8.8 k
44 k-ft
M
If using A992 Steel : FY = 50 ksi
Fb = Mmax / Srequired
SRequired = Mmax / Fb
SRequired = 528 k-in / 30.0 ksi = 17.6 in3
Finding Internal Forces : Graphic Method
ω = 880 lb/ft
Mmax = 44 k-ft
0 lb
20 ft
8.8 k
8.8 k
Allowable Bending Stress :
P
Fb = 0.60 FY = 0.60 (50 ksi) = 30.0 ksi
Mmax = 44 k-ft (12 in / ft) = 528 k-in
8.8 k
fb = M/S
V
10 ft
- 8.8 k
44 k-ft
M
If using A992 Steel : FY = 50 ksi
Fb = Mmax / Srequired
SRequired = Mmax / Fb
SRequired = 528 k-in / 30.0 ksi = 17.6 in3
USE W10x19, SX-X = 18.8 in3
Vertical Load Flow :
Tributary Area is the area that contributes load
to a specific structural element.
Tributary Strip is the width of area that
contributes load to a specific element.
spanning behavior and critical metric
L = 20 ft
If using wide flange steel
beam:
depth = L/18 = 1.11 ft = 13 in
(conservative)
W14 or W16 is a good
approximate size
L = 30 ft
If using flat reinforced
concrete slab:
depth = L/25 = 1.2 ft = 14.4 in
(conservative)
a 14 in thick slab is a good
approximate depth
column (compression strut) review
buckling shape
slenderness ratio = kl/r
L = unbraced length
compression and slenderness
slenderness ratio = kl/r
k = effective length coefficient
(boundary condition affect)
slenderness ratio = kl/r
r = radius of gyration
wood sections:
r = I/A
I = 1/12 b h3
slenderness ratio = kl/r
r = radius of gyration
steel sections - look up in table
range kl/r: 60-80 for columns
100-120 for trusses
r = radius of gyration
concrete sections:
r = 0.3 h (rectangular sections)
r = 0.25 h (circular sections)
slenderness ratio = kl/r
range kl/r: 40-60 columns
h (dia) = 12 in r = 0.3 h = 3.6 in
assume k = 1.0
l = 15’-0” = 180 in
kl/r = (1.0)(180 in) / 3.6 in
kl/r = 50
wind load (WL)
event lateral and uplift load caused by
windward and leeward wind pressure
(high mass helps resist overturning
and increases foundation friction)
earthquake load (EQ)
event lateral and vertical loads caused
by the acceleration of building mass
due to ground motion generated from
a fault rupture. (mass and height
increase lateral and vertical load)
3RD FLOOR LATERAL LOAD FLOW
STRUCTURAL SYSTEM
FORCE / Loads (ACTION)
MATERIAL : strength, stiffness, elasticity and ductility
CONFIRGURATION of components
ASSEMBLY : boundary conditions, joints (fixity), assembly hierarchy
CONFIRGURATION of assembly
FORCE FLOW (REACTION)
moment frame review
shear wall review
Long (Shear) Walls / Cores
(vertical cantilever)
surface/strut+tie action
L/d < 3
Tall (Flexural) Walls / Cores
(vertical cantilever)
bending action
L/d > 6
shear wall to core
tube systems
Swiss Re
diagrid tube systems
Architect : Norman Foster
