钢筋混凝土梁的弯曲性能尺寸效应试验研究

Experimental Study on Size Effect of Flexural Behavior of Reinforced Concrete Beams

进行了抗压强度为46.5～50.6MPa,截面高度为250～1 000mm的钢筋混凝土试件弯曲性能试验。与相同尺寸和配筋的高强混凝土试件(fcu=72.1～72.4MPa)的试验结果进行了对比分析,从受弯承载力和变形能力两个方面研究了钢筋混凝土试件的受弯性能尺寸效应。研究表明,截面尺寸的变化对钢筋混凝土构件的名义开裂弯矩、屈服弯矩和极限弯矩没有明显影响,对位移延性和塑性铰区塑性转动能力有显著影响,试件的位移延性系数和塑性铰转动能力随截面高度的减小而减小,并且普通混凝土试件和高强混凝土试件的尺寸效应规律基本相同,与混凝土强度无关。试验结果表明,不同混凝土强度和截面高度试件的塑性铰区长度均为1倍截面有效高度。

Reinforced concrete specimens with concrete compressive strength varied from 46.5 to 50.6 MPa and with depth of cross section from 250 mm to 1 000 mm subjected to bending were tested.Size effects of flexural behavior with respect to bending capacity and deformation capacity were investigated based on the analysis of the test results and those of high-strength specimens(fcu=72.1~72.4 MPa) of which the geometry and reinforcement layouts were identical to those of specimens tested in this study.It is shown that beam depth does not has any apparent influence on nominal cracking moment,nominal yield moment and nominal ultimate moment,and that it has significant influence on displacement ductility and plastic rotation capacity of plastic hinges of members.For normal-strength concrete specimens and high-strength concrete specimens,both the displacement ductility and the plastic rotation capacity decrease with the increasing of depth in the similar ways,and are independent of concrete strength.It is also demonstrated that the lengths of plastic hinges of members with different depth and concrete strength are approximately equal to the depth.