钢混组合梁负弯扭作用下的受力性能试验研究

Experimental research on mechanical behavior of steel-concrete composite beams under combined negative bending moment and torque

为了研究钢—混组合梁在负弯矩和扭矩联合作用下(以下简称负弯扭)的受力性能,以初始扭弯比和抗剪连接度为参数,对4片钢—混凝土组合箱梁分别进行不同偏心距下的反向集中力加载实验,得到了荷载—挠度和荷载—扭转角曲线、截面应变和结合面纵横向滑移分布规律,以及混凝土板裂缝开展规律。试验结果表明:在负弯扭联合作用下,组合梁极限承载力和结合面抗剪刚度均随初始扭弯比的减小和剪力连接度的增加而增大;横隔板对截面应变沿横向的分布规律影响较大,有横隔板处,加载侧应变较小,相反侧应变较大;无横隔板处相反;仅受弯矩时混凝土板裂缝为横向裂缝,负弯扭作用下出现倾角40°左右的斜裂缝,横向钢筋的设置对裂缝间距影响较大。

In order to research the mechanical behavior of the steel-concrete composite beam under combined negative bending moment and torque,with the shear connection degree and torsionbending ratio as parameters,4 steel-concrete composite box beams were designed,and the negative bend-torsional experiment under upward concentrated load with different eccentricity were conducted. The change of the load-deformation,the load-twisted angle,strain distribution,slip between the concrete slab and steel girder and the cracking of concrete,were obtained. The resultsshow that,with the decrease of the torsion-bending ratio and the increase of the shear connection,the ultimate bearing capacity of the composite beam increases under the combination of negative bending moment and torsion. The effect of the diaphragms on the distribution of normal strain along the transverse direction is significant. At the point with the diaphragms,the strain is small at the loading side,but large at the other side,while at the point without diaphragm,the tendency is opposite. The cracks of concrete slab is along the transverse direction under only negative bending moment,while under the combined negative bending moment and torque,the cracks are inclined at an angle of about 40 degrees. The transverse reinforcements have a great influence on the crack spacing.