三点弯曲下混凝土梁挠度与裂缝口张开位移关系  

Relationship of deflection and crack mouth opening displacement of concrete beams under the three-point bending

作　　者：王青原[1] 陈红鸟[1] 张华刚[1] 刘春[1] 赵艳兵[1] 黄兴震 

机构地区：[1]贵州大学空间结构研究中心,贵阳550003

出　　处：《应用力学学报》2017年第5期937-943,共7页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(51408144;51568012);贵州省科学技术基金项目([2016]1040);贵州省留学人员科技创新项目(Z164096);贵州大学引进人才科研基金([2013]01)

摘　　要：为研究三点弯曲混凝土梁挠度δ与裂缝口张开位移CMOD的关系,对五组尺寸相同、强度不同的预制切口梁进行三点弯曲试验,获得加载全过程的P-δ曲线和P-CMOD曲线。由于试验中的P-δ曲线和P-CMOD曲线同步测得,取相同P值下对应的δ值与CMOD值,即可得到一一对应的δ值与CMOD关系。分析表明:δ-CMOD关系可分为非线性和线性两部分,采用数值分析确定两部分的拟合参数;针对混凝土强度的影响,提出各参数关于强度的经验公式。最后,通过对不同批次、相同成分的混凝土断裂能对比分析,证实了本文拟合关系的可靠性。采用本文公式由CMOD计算的断裂能G_F^(P-δ(CMOD))的标准偏差为5.93N/m,远小于由挠度实测值计算的断裂能G_F^(P-δ)的标准偏差21.05N/m,且G_F^(P-δ(CMOD))的平均值更接近已知的混凝土的断裂能。In order to study the relationship of deflection(δ) and crack mouth opening displacement(CMOD) of concrete beams, three-point bending tests are performed on five groups of pre-notched concrete beams with the same geometry but different compressive strengths. The entire load-displacement curves including P-δ curves and P-CMOD curves are recorded by a data logger. Experimental results indicate that the δ-CMOD curves include two parts: nonlinear part and linear part. The δ-CMOD relationships are fitted by polynomial formulas. The parameters of the formulas and influence of compressive strengths on the parameters are evaluated. Finally, the reliability of present formulas is verified by analyzing the fracture energies of concrete with the same mix proportions but in different batches. The standard deviation of G_F^(P-δ(CMOD))(5.93N/m) calculated from the P-CMOD curve is much lower than that of G_F^(P-δ) (21.05N/m) calculated using the P-δ curve, and the average of the G_F^(P-δ(CMOD)) is closer to the known fracture energy.

关 键 词：混凝土 三点弯曲 挠度 CMOD 断裂能 

分 类 号：TU528[建筑科学—建筑技术科学]