折线预应力配筋先张法混凝土T梁的应力集中控制措施  

ControlMeasures of Stress Concentration Effect of Polyline Pre-stressed Pretensioned Concrete T-beam

作　　者：朱华 郭增伟 谢新龙 刘兵 ZHU Hua;GUO Zengwei;XIE Xinlong;LIU Bing(School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China;Jiangxi Provincial Expressway Investment Group Co.,Ltd.,Nanchang 330025,China;Jiangxi Province traffic construction engineering quality supervision administration,Nanchang 330008 China)

机构地区：[1]重庆交通大学土木工程学院,重庆400074 [2]江西省高速公路投资集团有限责任公司,南昌330025 [3]江西交通建设工程质量监督管理局,南昌330008

出　　处：《结构工程师》2020年第1期33-39,共7页Structural Engineers

基　　金：国家自然科学基金(51878106,51408087);重庆市自然科学基金(cstc2019jcy-msxmx0818)。

摘　　要：针对折线先张法混凝土T梁预应力弯折位置处应力集中的问题,以ANSYS有限元分析软件为工具,采用钢筋混凝土整体式模型,建立了折线预应力混凝土T梁的非线性有限元实体分析模型,分析了先张梁预应力筋折点部位应力集中现象的特点,探讨了T梁纵向、竖向、横向配筋率以及钢束弯起半径对弯折点附近应力集中现象的影响。研究发现:先张梁预应力筋弯折点附近有明显的应力集中现象;随着钢束弯起半径的增加,应力集中系数呈现先减小后增大的趋势;普通钢筋的加入能够有效改善应力集中现象,会使折线预应力钢筋弯起位置的拉应力分布的更加均匀,其中竖向钢筋(梁高方向)对应力集中现象的改善效果最为明显;配筋率低于《公路桥梁通用图》中构造钢筋配筋率时,预应力弯折点附近平均应力、最大拉应力随配筋率的增大而减小,当配筋率超过基准值后折线钢束弯折点附近应力有增加趋势,对于35 m简支T梁,当各个方向的普通钢筋按照0.8~1.0倍《公路桥梁通用图》中构造配置时,能最大程度地减弱折线配束造成的混凝土应力集中现象。Aiming at stress concentration phenomenon at pre-stressed bending position of the pre-tensioned concrete T-beam,the ANSYS finite element analysis software was used as a tool to establish a nonlinear finite element analysis model of the pre-stressed concrete T-beam.Caracteristics of stress concentration in the fracture point of the pre-stressed tendon of the pre-tensioned beam are analyzed.Effects of the longitudinal,vertical,transverse reinforcement ratio of the T-beam and the bending radius on the stress concentration near the bending point are discussed.This study found that there is obvious stress concentration in the pre-stressed tendon of the pre-tensioned T-beam.With the increase of the bending radius of pre-stressed reinforcements,the stress concentration factor decreases first and then increases.The addition of ordinary steel can effectively improve the stress concentration phenomenon,especially the vertical reinforcement.When the reinforcement ratio is lower than the structural reinforcement ratio in General Design of Highway Bridges,the average stress and the maximum tensile stress near the pre-stressed bending point decrease with the increase of the reinforcement ratio.When the reinforcement ratio exceeds the reference value,the stress near the bending point increases.For 35 m simple-supported T-beams,when the reinforcement ratio in all directions are constructed in accordance with 0.8~1.0 times of General Design of Highway Bridges,the stress concentration phenomenon in the fracture point can be minimized.

关 键 词：有限元法 应力集中 折线配筋 折点半径 配筋率 

分 类 号：U445.57[建筑科学—桥梁与隧道工程]