型钢混凝土梁截面抗弯刚度取值方法的分类比较与验证

Classification Comparison and Verification of Section Bending Stiffness Determination Methods of Steel Reinforced Concrete Beams

对国内外相关研究进行深入的梳理与分析后发现:(1)现有的取值方法可分为两个层次:用于整体结构分析的宏观方法和针对构件层次的精细方法;(2)在第一层次的方法中,早期方法可归纳为折算刚度法,当前主流方法可归纳为分材直接叠加法;(3)在第二层次的方法中,主流方法均为直接叠加法的修正:叠加对象可以增加约束混凝土,修正对象一般是对钢筋混凝土部分的刚度,少数情况下是型钢部分的刚度;同时考虑了荷载的长期作用效应,区分了短期刚度与长期刚度;(4)综合准确性与简便性,最值得推荐的是《组合结构设计规范》方法。方法计算值与试验值的比较表明:计算值比较准确,略偏于保守;方法中隐含考虑的梁体内部状态,可认为是梁所受弯矩达到极限弯矩一半左右的状态。

After in-depth combing and analysis of related research at home and abroad,it is found that:(1)the existing value-taking methods can be divided into two levels:the method for overall structural analysis and the refined method for member levels;(2)For the first-level methods,the earlier methods can be summarized as the reduced stiffness method,and the current mainstream methods can be summarized as the direct superposition method;(3)For the second-level methods,the mainstream methods are the modification of direct superposition methods.The constrained concrete can be added as superposition object.Stiffness of the reinforced concrete part is generally employed as modification object.In a few cases,the stiffness of the steel section is employed as modification object.Simultaneously,the long-term effect of load has been considered and then the short-term stiffness and long-term stiffness are distinguished;(4)Considering accuracy and simplicity,the most recommended method is the Code for Design of Composite Structures method.The comparison between the calculated value of this method and the experimental value shows that the calculated value is accurate and slightly conservative.The beam body internal state considered implicitly in this method can be considered as the state when the bending moment of the beam reaches about half of the ultimate bending moment.