往复加载下预制承台-桩连接构造受力性能

在交通不便、土地资源稀缺及环保要求高的山区公路高架桥梁建设中，为充分利用一体化架桥设备桥面输送预制构件的优势、最大限度地实现全预制桥梁的建造需求，提出一种将现浇承台改为预制承台的方案。针对预制承台与桩连接构造受力安全可靠性问题，按照1/3的缩尺比设计制作两个预制承台-桩连接构造试件和一个现浇承台-桩连接构造试件，进行往复加载试验与非线性数值分析。试验结果表明：与现浇承台试件相比，预制承台试件的屈服点、极限承载力基本相同，桩的抗裂性能、裂缝分布也基本一致；现浇承台更易开裂，但预制承台裂缝数量更多、最大裂缝宽度更大；桩-预制承台连接试件的初始刚度略小，但开裂后的刚度与现浇承台试件相同；两种承台均能与桩共同受力，整体性能够得到保证。数值模拟与试验的倾角-位移曲线和滞回曲线较好吻合，表明数值模型可反映试件的变形情况、承载力与捏缩特性。试验和数值分析均验证了预制承台-桩连接构造受力性能的可靠性。

Mechanical performance of precast pile cap-to-pile connection under cyclic loading

 In the construction of mountainous highway viaduct bridges with inconvenient traffic, scarce land resources and high environmental protection requirements, in order to make full use of the advantages of integrated bridge erecting machines and maximally realize fully precast bridge construction, an alternative method of inverting cast-in-situ pile cap to precast pile cap was proposed. To investigate the safety and reliability of the connection between precast pile cap and pile, two 1/3-scale precast cap-to-pile connection specimens and one 1/3-scale cast-in-situ cap-to-pile connection specimen were designed and manufactured. The analysis of the specimens was conducted using cyclic loading test and nonlinear numerical analysis methods. The test results show that the yield points and bearing capacities of precast cap specimens are basically the same as those of cast-in-situ cap specimen, as well as the crack resistance and crack distribution of piles. The crack load of cast-in-situ cap is smaller than those of precast pile caps, but the number of cracks and the maximum crack width of the precast caps are larger. The initial stiffness of the pile-precast cap specimen is slightly smaller, but the post-cracking stiffness is the same as the cast-in-place cap specimen. Both two kinds of caps can work together with piles, so the integrity of structures can be guaranteed. The hysteresis curves and inclination-displacement curves obtained by numerical analysis are in good agreement with the test results, indicating that the numerical models well predict the deformations, bearing capacities and pinch characteristics of the specimens. Both test and numerical analysis results verified the reliability of the mechanical performance of the proposed precast pile cap-to-pile connection construction.