基于桁架-拱模型的钢筋UHPC矩形梁抗剪承载力计算方法  

Research on Shear Capacity of UHPC Rectangular Beams Based on Truss-arch Model

作　　者：余自若[1] 夏文敏 安明喆[1] 王月[1] 韩松[1] YU Ziruo;XIA Wenmin;AN Mingzhe;WANG Yue;HAN Song(School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]北京交通大学土木建筑工程学院,北京100044

出　　处：《铁道学报》2023年第3期16-29,共14页Journal of the China Railway Society

基　　金：中央高校基本科研业务费(2019JBM089);国家自然科学基金(52108189,51878033)。

摘　　要：超高性能混凝土(Ultra-high Performance Concrete, UHPC)在铁路桥梁中有着广阔的应用前景,UHPC梁的抗剪承载力计算是UHPC结构设计的重要部分。针对钢筋UHPC矩形梁,利用数值分析方法,分析剪跨比、纵筋配筋率、箍筋配筋率、钢纤维掺量等各因素对梁抗剪承载力的影响;在传统桁架-拱模型的基础上单独考虑钢纤维的增强作用,把钢纤维作为桁架模型中的受拉斜腹杆并根据厚壁圆筒原理推导钢纤维提供的抗剪承载力,结合UHPC的材料特征和UHPC矩形截面构件的抗剪设计特点,建议斜压腹杆倾角和软化系数等关键参数的取值,提出能考虑钢纤维掺量和几何特征的UHPC矩形梁抗剪承载力计算公式;以国内外147根UHPC矩形梁的抗剪试验结果验证计算方法的正确性和适用性。结果表明:建议的UHPC矩形梁抗剪承载力公式计算结果与实测值吻合较好,相比常用的国外UHPC结构设计规范建议方法,方法得到的结果与实测值更为接近;钢纤维对梁的抗剪承载力有显著贡献;纤维掺量和纤维几何特征对梁的抗剪承载力有明显影响。Ultra-high performance concrete(UHPC)has broad application prospects in railway bridges.The calculation method of shear capacity of the UHPC beam is an important part of UHPC structural design.In this paper,numerical analysis method was used to analyze the effect of shear-span ratio,longitudinal reinforcement ratio,stirrup reinforcement ratio,and steel fiber content on the shear bearing capacity of reinforced UHPC rectangular beams.Based on the traditional truss-arch model,the reinforcement of steel fibers was considered separately.With steel fibers being used as tensile diagonal webs in the truss model,the shear bearing capacity provided by steel fibers was calculated according to the principle of thick walled cylinder.Combined with the characteristics of UHPC material and the shear design characteristics of UHPC rectangular members,the key coefficients such as the inclination angle of diagonal compression web member and softening coefficient were suggested.Then a formula for calculating the shear capacity of UHPC rectangular beams that can consider the steel fiber content and geometric characteristics was proposed.The correctness and applicability of the calculation method were verified by the shear experimental results of 147 reinforced UHPC beams.The results show that the calculated values are in good agreement with the experimental values and are closer to the tested values than those suggested by the commonly used design codes for UHPC structures abroad.Steel fibers have a significant contribution to the shear capacity of UHPC rectangular beams.The fiber content and fiber geometric characteristics have obvious effects on the shear capacity of beams.

关 键 词：UHPC 矩形梁 桁架-拱模型 钢纤维 抗剪承载力 

分 类 号：TU398.9[建筑科学—结构工程]