中文摘要：

为研究竖向荷载作用下单层单跨组合梁钢框架的刚度，将组合梁钢框架中的梁简化为阶梯形变截面梁，进行参数确定；应用试验值验证ANSYS有限元程序分析组合梁钢框架的可行性，利用此程序进行组合梁钢框架的非线性分析，确定了组合梁钢框架在竖向荷载作用下的负弯矩区长度参数，从而建立了该组合梁刚度计算模型．采用等效原理，确定出竖向荷载作用下单层单跨组合梁钢框架的等效剐度计算公式，给出工程设计时刚度取值的建议，并与有限元分析结果进行了对比．结果表明：理论分析和推导与ANSYS有限元分析结果吻合很好．

英文摘要：

To study the stiffness of single-bay-span steel frames with steel-concrete composite beams under vertical loads,parameters of the steel-concrete composite beam in steel frames were determined by simplifying the beam as the variable cross-section ladder-type one. The feasibility of analyzing steel-concrete composite beams of steel frames by using the finite element analysis program ANSYS was validated by test data. Through the nonlinear analysis of steel frames with steel-concrete composite beams,the length parameters of negative moment district under vertical load were obtained, and a calculation model for stiffness analysis was established. According to the equivalent principle, the stiffness of steel-concrete composite beams in steel frames was ana- lyzed. The equivalent stiffness formula of steel-concrete composite beams in steel frames under vertical loads was derived on the basis of dominant cross - section deflection equality principle. By comparing with the results of the proposed calculation model with those of the finite element analysis in ANSYS, it is shown that there is a good agreement between them,which verifies the correctness of the proposed model.