Challenge the future
DelftUniversity ofTechnology
Extended Strip Model for slabs
subjected to a combination of loads
Eva Lantsoght, Cor van der Veen, Ane de Boer
2
One-way vs. two-way shear (1)
Beam shear, one-way shear Punching shear, two-way shear
• Punching shear over perimeter• Beam shear over
(effective) width
3
One-way vs. two-way shear (2)
• 3D representation of failure modes
4
Slab bridge under live loads
5
Strip Model (1)
• Alexander and Simmonds, 1990
• For slabs with concentrated load in middle
• Lower bound method: conservative
6
Strip Model (2)
7
Extended Strip Model (ESM)
• Effect of geometry• Effect of bending moment
diagram: L, aM
• Effect of torsion β• Effect of self-weight vDL
• Unequal loading of strips v1 and v2
• Size effect on wACI
8
Extended Strip Model for
combination of loads (1)
9
Extended Strip Model for
combination of loads (2)
ESM x sup y edgeP P P P P
, ,2 1x sag x ACI xP M w
, ,
22 1x
sup s x ACI x
v
dP M w
a
, ,2y s y ACI y DL dist
M
LP M w v v
L a
, ,
,
2 for
for
s y ACI y DL dist w edge
M
edge
ACI y DL dist edge w edge
M
LM w v v l l
L aP
Lw v v l l l
L a
1
3
,
100mm0.166ACI x y ckw d f
d
1
3
,
100mm0.166ACI y x ckw d f
d
,
,
2 s y
w
ACI y DL dist
M
Ml
Lw v v
L a
10
Comparison to experiments (1)
Comparison between experimental results and ESM, 23 experiments on slabs under combination of loads for validation
11
Comparison to experiments (2)
• Pconc/PESM:• Average: 1.47
• COV: 12.5%
• 5% lower bound: 1.17
• Safe and conservative
method for assessment
Test setup in Stevin II lab of Delft University of Technology
12
Summary & Conclusions
• Transition between one-way and two-
way shear
• Slabs under combination of loads =>
live load models
• Strip Model for concentric punching
shear, slab-column connections
• Extended Strip Model for slab bridges
• 23 experiments under combination of
loads for validation of ESM
• ESM provides safe lower bound for
assessment