梁柱不同混凝土强度的高层框架节点试验和有限元分析

高层框架结构设计时，梁板与柱常常会采用不同的混凝土强度等级，柱的混凝土强度等级往往高于梁板。对于梁柱的节点，一般多采用与柱相同的强度等级，这给施工带来很大麻烦，如果采用与梁板相同强度等级混凝土时。虽然方便了施工，但降低了节点的抗震性能。本文的研究是通过对此类节点采取加强措施，以弥补混凝土强度等级降低的不利影响。通过节点模型试验，研究其受力性能及破坏机理，验证加强措施的有效性。并在试验研究的基础上，用有限元方法对受力复杂的节点进行分析，结果表明节点区混凝土存在应力集中和应力扩散现象以及存在混凝土侧向受拉的现象．证实了梁加腋和增设X型钢筋后节点受力性能得到了改善和加强。这些研究成果对目前高层建筑梁柱节点采用不同混凝土强度等级的设计、施工提供了有益的参考。

Tests and Finite Element Analysis of Frame Joints (Beams and Columns with Different Grade Concrete) in Tall Building

On tall building frame structure design, beams (plates) and columns usually have different grade concrete. The concrete strength of columns is usually higher. Generally, the joints are the same grade concrete as columns. This would cause a big difficulty to the construction. If taking identical strength, the earthquake resistant ability of frame joint will be weak although it is convenient for construction. The strengthening method to offset negative effect of different grade concrete was studied. Though joints model tests, the characteristics of load bearing and fracture mechanism were investigated, and the strengthening methed was verified. Based on the tests, the finite element method was used to analyze the complicated mechanism of joints. The results indicate that the stress concentration, stress dispersion and laterally tension occur in the joint area of concrete. Consequently, the joints characteristics of load bearing will be enhanced after haunched beam and supplement X-bar. It is suggestible to the design and construction for beams, columns and joints with different strength in tall building.