将以下的句子降重之15以内：在此试验基础上Darwin D等30-31提出了腹板开洞组合梁洞口截面承载力计算方法-弯剪相关曲线即在Redwood提出的模型基础上完善了弯矩-剪力相关关系用三次曲线代替二次曲线如图 1 3所示该方法将腹板开洞组合梁在弯矩和剪力共同作用下承载力的计算转化为计算洞口截面处的纯弯承载力 和纯剪承载力 即腹板开洞组合梁在极限承载力的状态下洞口处的弯矩 和剪力 应满足式1-1所

Darwin D et al. [30-31] proposed a method for calculating the cross-sectional load capacity of a web-holed composite beam, called the bending-shear correlation curve, based on the experiment. This method improves the correlation between bending moment and shear force by replacing the quadratic curve with a cubic curve in Redwood's model. As shown in Figure 13, this method converts the calculation of the load capacity of the web-holed composite beam under the combined action of bending moment and shear force into the calculation of the pure bending and pure shear capacity at the hole section. That is, at the state of ultimate load capacity of the web-holed composite beam, the bending moment and shear force at the hole section should satisfy the bending-shear correlation equation shown in Equation (1-1): (1-1) where M and V are the designed values of the bending moment and shear force at the center of the hole under the action of loads, respectively; η is the load resistance coefficient, which is 0.85; M_p and V_p are the pure bending and pure shear capacities at the center of the hole, respectively.