摘要
不同受剪承载力计算公式对混凝土强度、剪跨比、纵筋配筋率和截面尺寸等影响因素的考虑方式差别较大,基于收集、整理的集中荷载作用下轻骨料混凝土(LAC)梁的受剪试验数据,按照变量分离的方法,对各国规范建议计算式和经典的计算模型进行对比分析。结果表明:无论是规范计算式(JGJ/T 12−2019、ACI 318-19、BS 8110-1:1997)还是计算模型(Bazant-Sun、Kim-Park、Rebeiz、Vecchio-Collins),安全度均偏低。基于分析结果,确定各影响因素对LAC无腹筋梁抗剪承载力的影响,参照Vecchio-Collins计算模型的形式,引入参数λ考虑剪跨比的影响,并考虑到我国使用立方体抗压强度作为混凝土各种力学指标的代表值,通过对试验数据进行非线性拟合,进而提出修正计算式。从正常使用状态裂缝宽度控制和有腹筋梁承载力两方面对以修正计算式为混凝土项、箍筋项采用45°桁架模型建立的计算公式进行验算,结果表明该式与试验结果吻合良好,具有较好的计算精度。最后,将修正公式转换为与规范做法对应的设计值公式,并基于试验数据,给出了材料强度区间,供工程设计参考。
Different formulas have different ways to consider the factors of concrete strength,shear span ratio,reinforcement ratio and section size.Based on the test data of lightweight aggregate concrete(LAC)beams under concentrated load,the formula and model are compared and analyzed according to the method of variable separation.The results show that both the formulas(JGJ/T 12−2019,ACI 318-19,BS 8110:1997)and the models(Bazant-Sun,Kim-Park,Rebeiz,Vecchio-Collins)are not safe.According to the results,the influence of various factors on the shear capacity of LAC beams without web reinforcement is investigated.Referring to the form of Vecchio Collins model,the shear span ratioλis introduced.With the cubic compressive strength as the representative value of various mechanical indexes of concrete in China,the nonlinear fitting of test data is carried out,and then the modified formula is put forward.The modified formula is checked from the aspects of crack width control and bearing capacity of beams with web reinforcement,and the results show that the modified formula can meet the requirements well.According to the design habit of China,the modified formula is converted into the form of design value expression,and according to the test parameter interval of the database,the corresponding provisions of material strength are made,so as to be used in engineering design.
作者
张望喜
吕炜磊
胡彬彬
王冠杰
易伟建
ZHANG Wang-xi;LÜWei-lei;HU Bin-bin;WANG Guan-jie;YI Wei-jian(Hunan Provincial Key Lab on Diagnosis for Engineering Structures of Hunan University,Changsha,Hu’nan 410012,China;Civil Engineering College of Hunan University,Changsha,Hu’nan 410012,China)
出处
《工程力学》
EI
CSCD
北大核心
2022年第3期212-221,232,共11页
Engineering Mechanics
基金
国家自然科学基金项目(52078201)。
关键词
钢筋轻骨料混凝土梁
受剪承载力
模型误差评析
非线性拟合
修正公式
reinforced lightweight aggregate concrete beam
shear capacity
model error analysis
nonlinear fitting
correction calculation
