钢-混凝土连续组合梁在负弯矩区发生开裂后,由于剪切位移的影响,同一截面高度处钢筋的应力存在剪力滞后效应。由于开裂前后组合梁截面刚度发生变化,使负弯矩区钢筋的剪力滞效应势必受到混凝土开裂的影响。基于换算截面法和能量变分原理,并考虑混凝土开裂的影响,分别推导了反向跨中集中荷载和反向两点对称荷载作用下钢-混凝土简支组合梁的控制微分方程,最后通过叠加原理分析了连续组合梁的剪力滞效应,并与试验结果进行了对比。分析表明使用变分原理和叠加原理分析钢-混凝土连续组合梁是可行的,混凝土开裂使连续组合梁剪力滞系数分布规律发生变化,在开裂边缘剪力滞系数发生突变,但开裂长度对剪力滞效应影响不大。 After the steel-concrete continuous composite beam cracks in the negative bending moment zone, due to the influence of shear displacement, there is a shear lag effect on the stress of the steel bar at the same cross-section height. Due to the change of the section stiffness of the composite beam before and after cracking, the shear lag effect of the reinforcement in the negative moment area is bound to be affected by the concrete cracking. Based on the converted section method and the energy variational principle, and considering the influence of concrete cracking, the governing differential equations of steel-concrete simply supported composite beams under two-point symmetrical load in the reverse span direction and in the reverse direction respectively are derived. Finally, The principle of shear lag effect of continuous composite beams is analyzed and compared with the experimental results. The analysis shows that it is feasible to use the principle of variational principle and the superposition principle to analyze the steel-concrete continuous composite beam. The concrete crack causes the variation of the shear lag coefficient of the continuous composite beam to change, and the shear lag coefficient changes suddenly at the cracked edge. However, Force hysteresis effect has little effect.