框架桥节点UHPC桥面板负弯矩性能研究

Research on Negative Moment Bending Behavior of UHPC Layer on Frame Bridge Joints

研究目的:为探究小跨径连续框架桥负弯矩区UHPC桥面板的受力性能,通过实桥缩尺模型对节点抗裂、转动能力和极限承载力等进行试验研究,并基于ABAQUS有限元软件对试验模型进行数值模拟与参数分析,探究UHPC桥面板长度、厚度与配筋率等关键参数对框架桥负弯矩区节点受力性能的影响规律。研究结论:(1)框架桥节点的UHPC桥面板具有较高的开裂应力(6.56MPa),在正常使用阶段,UHPC桥面板有效抑制了负弯矩区的裂缝形成和发展,提高了结构的整体抗裂性能;(2)增大UHPC桥面板配筋率能有效提高框架桥节点的抗弯承载能力,但会降低UHPC桥面板的抗裂性能;(3)框架桥节点的抗裂性能与承载能力均随UHPC桥面板厚度的增大而提高;(4)在保证UHPC桥面板和UHPC-NC界面均具有较好抗裂性能的前提下,在框架桥节点的负弯矩零点之间设置UHPC桥面板经济性最好;(5)本研究就小跨径连续框架桥负弯矩区提出了一种高性能节点的构造设计方法,可为同类桥梁设计提供有效参考。

Research purposes:In order to investigate the mechanical performance of UHPC layer in the negative moment zone of small span continuous frame bridges,the crack resistance ability,rotation ability and ultimate bearing capacity of the joint were investigated by using the real bridge scaling model.Based on ABAQUS finite element software,the numerical simulation and parameter analysis of the test model were carried out to explore the effects of key parameters such as UHPC layer length,thickness and reinforcement ratio on mechanical performance of the negative moment joints of the frame bridges.Research conclusions:(1)The UHPC layer of frame bridge joint has a high cracking stress(6.56 MPa).In the normal use stage,the UHPC layer effectively inhibits the formation and development of cracks in the negative bending moment zone,and improves the overall cracking resistance of the structure.(2)Increasing the reinforcement ratio of UHPC layer can effectively improve the flexural bearing capacity of frame bridge joints,but will reduce the cracking resistance of UHPC surface layer.(3)The crack resistance and load bearing capacity of frame bridge joint increases with the increase of UHPC layer thickness.(4)On the premise that both the UHPC layer and the UHPC-NC interface have good crack resistance,it is the most economical to set the UHPC layer between the zero points of the negative bending moment of frame bridge.(5)The research results put forward a high performance joint design method for the negative moment zone of small span continuous frame bridge,which can provide an effective reference for similar bridge design.