Numerical methods in bridge structure analysis - Computational Analysis and Design of Bridge Structures - page 83

10058
8984

10055

9340

9027 9274

9340

8984 9274 9027 9167 9167

8986 8974 8906 8849 8905 8973 8985

10088

10090

7783

7782

5953 5953

4223 4223

2541 2542

891 892

−734 −731

−2334

−2338

−3903
−5339

−3902
−5344

−7070 −7055

−5579

−5775 −5772

−6348 −6250 −6257 −6348

−7005 −7014

Fx = 11.8939 Fy = 0.498916 Fz = −3.72129
Mx = −672.528 My = −702.866 Mz = 311822

Figure 3.11 Stress integration over a cross section comparing with beam theory.
Curves—axial stresses distribution from a shell element model. Straight
lines—axial stresses distribution recomputed from beam-bending theory by
using equivalent internal forces obtained from stress integration.

3.3 AutomAtIc tIme INcremeNtAl
creep ANAlySIS method

After elastic strains instantly occurred with loads on a concrete structure,
creep strains will later be developed. The development of creep strains
depends on the age of concrete when loads are applied and the time of
observing. However, the creep strains are always proportional to the initial
elastic strains that cause them. Creep strains affect a structure in two ways:
(1) extra displacements would be developed after construction and (2) extra
displacements would cause load redistributions. For concrete or compos-
ite bridge structures built in multiple stages, creep analyses are important
as loading and concrete aging history can be complicated. Together with