基于弥散裂缝理念的墩柱塑性铰区抗剪强度模型  

Shear strength model for plastic hinge region of column based on smeared-crack concept

作　　者：漆启明 邵长江[2] 杨华平 庄卫林[2] 崔皓蒙 王春阳 Qi Qiming;Shao Changiang;Yang Huaping;Zhuang Weilin;Cui Haomeng;Wang Chunyang(Chengdu University,Chengdu 610106,China;Southwvest Jicotong University,Chengdu 610031,China)

机构地区：[1]成都大学,四川成都610106 [2]西南交通大学,四川成都610031

出　　处：《土木工程学报》2024年第12期68-77,共10页China Civil Engineering Journal

基　　金：国家自然科学基金(51978581,51178395);四川省应用基础研究重点项目(2017JY0059)。

摘　　要：为避免强震作用下钢筋混凝土墩柱发生弯剪破坏,需准确量化墩柱塑性铰区抗剪强度。然而,现行规范和既有文献的抗剪模型普遍假定斜截面箍筋初始全部屈服、箍筋抗剪贡献随配箍率线性增大并与混凝土抗剪贡献直接相加,且对纵筋抗剪贡献重视不够,与实际弯剪损伤演化和试验规律不符。为此,借助弥散裂缝理念将钢筋混凝土视作一种新型均质材料,基于莫尔应力圆推导一种符合弯剪损伤演化且考虑混凝土、箍筋、轴力、纵筋、剪跨比及位移延性系数等因素的抗剪强度模型,并通过139个矩形墩柱试验数据进行标定和验证。结果表明:Eurocode 8模型过高估计了墩柱抗剪强度,Caltrans模型抗剪计算结果略微保守,而《公路桥梁抗震设计规范》(JTG/T 2231-01-2020)模型的抗剪计算值与试验值较接近;相比规范模型,建议抗剪强度模型具有更高的计算精度和更小的离散性,抗剪强度折减系数取0.85时的安全保证率达85%,可用于矩形墩柱塑性铰区的抗剪能力评估。To avoid flexure-shear failure of reinforced concrete column under strong earthquakes,it is important to accurately quantify the shear strength of plastic hinge region of column.However,the shear strength models from the current codes and existing literature generally assume that stirrups in diagonal section all yield at the initial stage.The shear contribution of the stirrups increases linearly with the stirrup ratio and is directly added to the shear contribution of concrete.Moreover,insufficient attention is paid to the shear contribution of longitudinal reinforcement.The above views are inconsistent with the actual flexure-shear damage evolution and experimental law.To this end,the reinforced concrete is taken as a new type of homogeneous material using the smeared-crack concept.Based on the Mohr stress circle,a shear strength model is derived that conforms to the flexure-shear damage evolution and considers factors such as concrete,stirrup,axial force,longitudinal reinorcement,shear span ratio,and displacement ductility coefficient.The shear strength model is calibrated and verified through the test data of 139 rectangular columns.The results show that the Eurocode 8 model overestimates the shear strength of the columns.The calculated value of Caltrans model is slightly conservative,while the calculated value of JTG/T 2231-01—2020 model is relatively close to the experimental value.Compared with the models in the design codes,the proposed shear strength model has higher calculation accuracy and smaller dispersion with a safety assurance rate of 85%under the shear strength reduction factor of 0.85.The research results can provide reference for the shear capacity assessment of the plastic hinge region of rectangular columns.

关 键 词：桥梁工程 钢筋混凝土墩柱 抗剪强度模型 塑性铰区 弯剪耦合损伤 

分 类 号：U442.5[建筑科学—桥梁与隧道工程]