钢筋混凝土框架边节点现浇板受拉有效翼缘宽度研究

现浇板参与受力会影响甚至改变钢筋混凝土框架节点的破坏模式，其对结构抗震性能的影响可通过计算有效翼缘宽度来反映。通过3个钢筋混凝土梁-柱-板边节点试件的低周反复荷载试验，对带现浇板的边节点破坏形态、滞回曲线以及现浇板纵向钢筋应变等进行了分析。研究结果表明：由于现浇板参与受力，增大了框架梁端弯矩，使得钢筋混凝土梁-柱-板边节点的下柱顶部发生破坏，未能实现“强柱弱梁”预期破坏机制；现浇板纵筋应变随层间侧移角增加而增大，在相同层间位移角下，板筋应变值随距梁侧距离的增大而减小。为进一步对钢筋混凝土梁-柱-板边节点的受力机理进行研究，以力学模型为基础建立了现浇板受拉有效翼缘宽度计算方法，根据建议公式对8组钢筋混凝土梁-柱-板边节点现浇板的有效翼缘宽度进行分析，计算结果与试验结果吻合较好，建议的计算方法有效解决了设计规范中经验公式计算结果离散性大的问题。

Effective flange width of cast-in-situ slab under tension for reinforced concrete exterior joints

The failure modes of reinforced concrete frame joints are influenced even transformed by the involvement of cast-in-situ slab in shear force input. Its effect on the seismic behavior of buildings was considered by calculating the effective flange width of cast-in-situ slabs. According to the tests on three reinforced concrete beam-column-slab exterior joint specimens under low cyclic reversed loading, the failure process, failure characteristics, hysteretic curves and the strain distribution of longitudinal reinforcements of slab for exterior joints with cast-in-situ slab were analyzed in the current study. Test results indicate that failure occurs at the top of bottom column for reinforced concrete beam-column-slab exterior joint due to the increasing moment of beam section by the involvement of cast-in-situ slab under tension. The anticipated ‘strong column weak beam’ philosophy is not successfully achieved. The strains of longitudinal reinforcements of slab increase with the increase of inter-story drift ratio, and the strains of longitudinal reinforcements of slab decrease with the increase of distance from the centerline of beam section for the fixed inter-story drifts. By analyzing the mechanical mechanism of reinforced concrete beam-column-slab exterior joint, a new method for calculating the effective flange width of cast-in-situ slabs under tension is suggested based on definite mechanical model. The suggested method is checked by test results of eight reinforced concrete beam-column-slab exterior joint specimens. The results show that the predicted effective flange widths agree well with the test results. It overcomes the drawback of great discreteness between the test results and the predicted results by the empirical formulas in current design codes.