考虑腹板斜裂缝的钢筋混凝土梁剪切变形测试分析  

Test and analysis on shear deformation of reinforced concrete beams with diagonal cracks

作　　者：史国刚[1] 赵桉[2] 刘钊[2] 

机构地区：[1]东南大学交通学院,江苏南京210096 [2]东南大学土木工程学院,江苏南京210096

出　　处：《长安大学学报（自然科学版）》2015年第4期62-68,共7页Journal of Chang’an University(Natural Science Edition)

基　　金：江苏省交通科学研究计划项目(2010Y12)

摘　　要：为研究腹板斜裂缝对钢筋混凝土梁剪切变形的影响程度,设计制作了以大标距机械式应变计为基础的框格应变测量装置,并通过模型试验等手段开展了测试与分析。试验采用1组小剪跨比混凝土工字梁试件,有等高度和变高度2种截面形式;在每个试件的腹板外侧,布置了5个框格应变测量装置,通过测量每一框格5个杆件的应变,应用理论模型推算出不同位置处框格的弯曲应变和剪切应变,实现斜裂缝开展前后应变的连续观测。研究结果表明:框格测试装置能实现梁体剪切变形与弯曲变形精确分离;薄腹梁腹板开裂后,剪切变形在总变形中的比例超过50%,箍筋屈服时,剪切变形可达到总变形的90%左右;配箍率与有效抗剪高度对开裂后剪切变形有显著影响;应用框格大标距的测试方法,有助于推动弹塑性极限状态下混凝土梁抗剪刚度的深入研究。To investigate the impact of inclined cracks on the shear deformation of reinforced concrete beams, long base strain gauges with mechanical dial were devised in grid pattern. Experimental tests were also conducted on beams with I-shaped cross-section and low shear span-to-height ratio. The specimens contain 2 beams with constant height and 2 beams with variable height. On the sides of the web surface, 5 rectangular panels instrumented with the tailor-made strain gauges were set to capture the mean strain continuously and to avoid the disturbance of cracking. By measuring the strains in five directions of each rectangular panel, bending and shear strains could be obtained via theoretic formulae. The results show that accurate separation between shear deformation and bending strain can be achieved by using grid strain-gauge instruments. Shear deformation accounts for more than 50% of total deformation after shear cracking and it can achieve about 90 % of total deformation in stirrup yielding. The method of long base grid strain gauges is conduced to deep research on shear stiffness under elastoplastic ultimate state. 3 tabs, 9 figs, 15 refs.

关 键 词：桥梁工程 应变测量装置 斜裂缝 剪切变形 剪应变 

分 类 号：U446[建筑科学—桥梁与隧道工程]