梁端预制拼接箱梁桥抗剪性能模型试验

Model experiment of shear performance of beam-end prefabricated spliced box girder bridge

针对预应力混凝土箱梁桥施工质量不易保证的问题,提出梁端预制拼接的施工方法;采用精细化加工的箱梁锚固端节段,通过剪力键与混凝土箱梁的现浇节段纵向拼接,从而避免由于施工原因造成的预应力箱梁桥长期性能退化.作为拼接箱梁桥受力的关键构件,梁端承受剪力作用的结合面的受力最为不利,因此本研究采用足尺模型试验和有限元计算的方法,对新型节段拼接混凝土箱梁桥抗剪性能进行研究.试验、有限元计算和参数分析结果表明,所建立的有限元模型能较好地模拟节段拼接箱梁桥在试验荷载作用下的抗剪性能;带剪力键的箱梁节段结合面是该类型桥梁受力最薄弱的部位;试验模型在试验荷载的作用下,其主要破坏模式是在箱梁节段之间传递剪力的剪力键发生破坏;桥梁抗剪极限承载力与剪力键尺寸成正比,与腹板剪力键和顶板剪力键的数量成正比,但与底板剪力键的数量关系不大.

Aiming at the problem that the construction quality of prestressed concrete box girder bridge is difficult to guarantee,the construction method of beam-end prefabricated splicing is put forward.The beam-end anchoring segment is precisely prefabricated,and longitudinally spliced with the fieldcast segments through shear keys,so as to avoid the long-term performance degradation caused by construction.As the key component of the spliced box girder bridge,the junction surface under the shearing force at the beam end is the most unfavorable,so this paper adopts the full scale model test and finite element calculation to study the shear performance of the new segmental spliced concrete box girder bridge.The results of test,finite element calculation and parameter analysis show that the finite element model can simulate the shear performance of segmental spliced box girder bridge under test load.The junction surface of box girder with shear key is the weakest part of the bridge.Under the action of test load,the main failure mode of the test model is the failure of the shear key that transfers the shear force between segments.The ultimate shear capacity of the bridge is proportional to the size of the shear keys and the number of the web shear keys and the roof shear keys,but has little relationship with the number of the bottom plate shear keys.