Reinforced concrete bridges - Computational Analysis and Design of Bridge Structures - page 118

z

x

Bent cap
(frame elements)

Columns
(frame elements)

Abutment
(frame elements)

Fixed supports

Figure 4.11 Example 1 skewed RC slab bridge modeling by CSiBridge.

25

20

Dead load
moment
Positive live
load moment
Negative live
load moment

15

10

5

0

−5

−10

−15

−20

Figure 4.12 Merlin-DASH example 1 dead and live load moment results (kip-ft).

The concrete slab is modeled with shell elements, whereas abutments are
modeled with frame elements. The bent caps and columns are also modeled
with frame elements. Their comparison results are shown in Figure 4.12
for Merlin-DASH line strip model and in Figure 4.13 for CSiBridge finite
element model, respectively. From Merlin-DASH program the maximum
positive moment for dead load is found to be 12.3 kip-ft/ft (54.7 kN-m/m),
whereas CSiBridge finite element model shows 286 kip-ft across the whole
normal width of 26.8′ (8.17 m), which is about 10.7 kip-ft/ft (47.6 kN-
m/m). As it is known that dead load distributions of a straight bridge
should be very close from one model to another or from one program to
another, the difference of this skewed example from a 2D to 3D model
reveals that the 2D modeling adopting an equivalent width is conservative