عنوان مقاله [English]
The construction of integral bridges solves difficulties due to the maintenance of expansion joints and bearings during serviceability; hence, it causes integral bridges to become more economic compared with conventional bridges. In the integral abutment bridge, the continuous deck slab and the abutments are integrated to form a rigid frame structure supported by single-row piles at the
abutments, and normally single-row H-piles with bending about their weak axis are used as a system that resists against lateral loads. However, single-row H-piles with bending about their strong axis and various pile types (H-piles, circular concrete piles, steel-concrete composite piles, etc.) with single-row or multi-rows have also been used. The embedded length of pile inside the abutment of the bridges has a key role in providing shear and flexural resistance of pile-pile cap connections.In this paper, first, a linear theoretical method was developed by authors to calculate the required embedded length of the pile, based on the plastic moment of steel pile. Then, the effect of spiral stirrup surrounding the steel pile was investigated in order to increase the strength of pile-pile cap connections. To evaluate the efficiency of theoretical method, finite element models were created. For this purpose, a finite element model was created based on existing experimental data. After the verification of this model with experimental data, five different finite element models were created with different embedded lengths. The results of nonlinear analysis showed that by
increasing of embedded length, the flexural strength of connection was increased, and also showed that the linear theoretical method was efficient in predicting required embedded length to resist flexural strength of the steel pile.To investigate the effect of spiral stirrup around the pile, one of the above five models was selected and finite element analysis was performed with and without surrounding spiral stirrup. Comparing the result of this analysis showed that using the spiral stirrup increased the flexural strength of pile-pile cap up to 58 percent.