Study on Interaction of RC Pile-Soil with High Reinforcement Ratio of Integral Abutment Bridges under Quasi-Static Test

In order to improve the ability of the reinforcement concrete (RC) pile foundation of integral abutment to absorb the horizontal reciprocating deformation under the action of temperature or earthquake, a pseudo-static low cycle test on interaction of pile-soil with high reinforcement ratio was carried out. The failure location, hysteresis curve, skeleton curve and horizontal deformation of three piles with different reinforcement ratios were compared. The test results show that, with the increase of the reinforcement ratio, the crack of the RC pile develops along the pile body to the depth, and the pile body failure area and the position where the maximum bending moment moves down, the crack resistance of the pile body is improved, and the effective interaction pile length increases; The test results also show that the hysteresis curve of the model pile becomes fuller with the increase of the reinforcement ratio, compared with the RCP-1 specimen with the lowest reinforcement ratio, the equivalent viscous damping ratio of the RCP-3 specimen is increased by 31.6%, and the energy dissipation capacity is improved. In addition, with the increase of the reinforcement ratio, the bearing capacity and deformation capacity of model piles are greatly improved. Compared with RCP-1 specimen, the ultimate bearing capacity of RCP-3 specimen increased by 150%, and the corresponding ultimate displacement increased by 153%. Increasing reinforcement ratio can significantly improve the mechanical properties and deformation capacity of RC pile.

Experimental Investigation on Dynamic Performance of Micro-Pile with Predrilled Oversize Hole on Shaking Table Test

For the situation of lacking research on micro-pile with predrilled oversize hole, the key part of semi-integral abutment bridge, the micro-pile-soil interaction shaking table test is carried out by considering the reaming pore diameter, depth, packing and other parameters in the end of the micro-pile to obtain the acceleration, pile moment, displacement and pile-system response frequency and other basic dynamic response and dynamic interaction law. Results show that: 1) the change of predrilled-hole parameters has litter effect on the dynamic properties of soil outside oversize hole; 2) The change of predrilled-hole parameters can cause the change of structural frequency, so led to the change of inertia force of pile head; 3) Inertial interaction has an important influence on the response of the upside part of pile and little influence in the downside part (lower than 15D). These conclusions will provide reference for dynamic response of interaction between pile with predrilled oversize hole and soil and make contribution to the practical application and designing of micro-pile with predrilled oversize hole.

Physical modeling of the long-term behavior of integral abutment bridge backfill reinforced with tire-rubber

The primary objective of this study is to investigate the benefits of adding tire rubber as an inclusion to backfill behind integral bridge abutments. In this respect, four physical model tests that enable cyclic loading of the backfill-abutment are conducted and evaluated. Each test consisted of 120 load cycles, and both the horizontal force applied to the top of the abutment wall and the pressures along the wall-backfill interface is measured. The primary variable in this study is the tire rubber content in the backfill soil behind the abutment. Results show adding tire rubber to the backfill would be beneficial for both pressure and settlement behind the abutment. According to results, adding tire rubber to soil decreases the equivalent peak lateral soil coefficient (Keq-peak) up to 55% and earth pressure coefficient ($${K}^{*}$$ K ∗ ) at upper parts of the abutment up to 59%. Moreover, the settlements of the soil behind the wall are decreased up to 60%.

The Response Modification Factor for Seismic Design of Integral Abutment Bridges

The response modification factor (R factor) is a crucial parameter for calculating the design seismic forces applied to a bridge structure. This factor considers the nonlinear performance of bridges during strong ground motions. Conventional bridge structures rely on the substructure components to resist earthquake forces. Accordingly, there are R factors available in the design codes based on the type of bridge substructure system. Lateral load resisting system of Integral Abutment Bridges (IABs) in the longitudinal direction is more complex than ordinary bridges. It involves the contributions from soils behind the abutments and soil/structure interaction (SSI) in addition to existing rigid connection between the superstructure and abutments. There is no R factor available in any design code throughout the world for IABs in the longitudinal direction that considers all these parameters. In this research, the Federal Emergency Management Agency publication FEMA P695 methodology has been applied to estimate the R factor for IABs. It is found that 3.5 could be a safe and valid R factor in the longitudinal direction for seismic design of such bridges.

Study of Horizontally Curved Slab-on-Steel I-Girder Bridges with Integral Abutments Under Thermal Loading

Integral abutment bridges have started to become part of the construction industry worldwide. However, they present challenges arising from the monolithic connection between bridge deck and the abutment. Thermal loading induced by daily cycles superimposed on seasonal cycles result in complex soil-structure interaction. Due to uncertainties in integral abutment bridge performance, there is no consensus among different codes on the bridge maximum length limit. A parametric study was carried out, using SAP2000 software, to examine the behavior of horizontal curved concrete slap-on-steel Igirders, under the effect of thermal loading conditions (±65°c). The self-weight of the bridge was considered. Spatial variables, including abutment height, radius of curvature, bridge span length, stiffness of backfill and types of foundation soil, were considered. The numerical analysis results were used to drive equation relating abutment height and bridge span with the maximum bridge length limit, which produces 40 mm horizontal displacement on pile head.

Study of Horizontally Curved Slab-on-Steel I-Girder Bridges with Integral Abutments Under Thermal Loading

Integral abutment bridges have started to become part of the construction industry worldwide. However, they present challenges arising from the monolithic connection between bridge deck and the abutment. Thermal loading induced by daily cycles superimposed on seasonal cycles result in complex soil-structure interaction. Due to uncertainties in integral abutment bridge performance, there is no consensus among different codes on the bridge maximum length limit. A parametric study was carried out, using SAP2000 software, to examine the behavior of horizontal curved concrete slap-on-steel Igirders, under the effect of thermal loading conditions (±65°c). The self-weight of the bridge was considered. Spatial variables, including abutment height, radius of curvature, bridge span length, stiffness of backfill and types of foundation soil, were considered. The numerical analysis results were used to drive equation relating abutment height and bridge span with the maximum bridge length limit, which produces 40 mm horizontal displacement on pile head.