单选题计算图所示压弯构件在弯矩作用平面内的稳定性时，等效弯矩系数应取何值进行计算？（　　）<br/> <br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/8325360_0.jpg"><br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/8325360_0_1.png">