EXPERIMENTAL STUDY ON STATIC BEHAVIORS OF SIMPLE-SUPPORTED DEEP RECTANGULAR BOX GIRDER

The elevated box girders would bear an additional large soil pressure and a vehicle load because of the backfilling of gulch and road construction caused by the function changes of urban lands. The change of a load case would result in the failure risk of a pipeline structure. The static properties of the reinforced concrete deep elevated box girders commonly used in the urban sewage pipeline system are experimentally analyzed. The failure pattern, shear lag effect and shear behavior of such deep box girders are studied. The shortages in the present design codes for the calculation of bending capacities of the box girders are also discussed. The box girder is simulated by using the non-linear finite element method. It is shown that under the vertical uniformly distributed load, the failure pattern of the simple-supported rectangular deep box girder with a depth-to-span ratio of nearly five is bending failure. The shear lag effect in the mid-span section is non-obvious, while it is more obvious before cracking in a quarter-span section. However, the lag effect is weakened gradually after cracking. The results simulated by the non-linear finite element method show an agreement with the experimental results. In order to avoid the premature cracking which affects the serviceability of a sewage pipeline, reinforcing measures should be carried out before the backfilling to the designed simple-supported sewage pipeline.