轴压比对预应力混凝土框架抗震能力影响研究

STUDY ON THE EFFECTS OF AXIAL COMPRESSION RATIO ON SEISMIC CAPACITY OF PRESTRESSED CONCRETE FRAME

由于预应力混凝土(PC)框架结构自身的特点,当采用我国现行规范规定的普通钢筋混凝土柱的轴压比限值进行设计时,往往会造成框架柱截面尺寸较小,在地震作用下结构形成典型的层间屈服机制而破坏;而过分限制轴压比,又会导致设计中"柱的截面尺寸由轴压比确定,柱的配筋则由构造配筋率确定",即:柱子的截面尺寸较大导致建造成本上升而经济性不佳,合理地确定柱轴压比已成为PC框架工程设计中的必需。依据我国现行规范设计设防烈度为8度(0.2g)区的6榀不同轴压比PC框架,采用基于性能的抗震分析评估理论,研究各轴压比下PC框架的耗能屈服机制及轴压比对PC框架抗震能力的影响,初步探讨PC框架轴压比限值的合理性与经济性。分析表明,进一步降低现行规范中的轴压比限值,能够较好地保证PC框架在罕遇地震作用下的抗震能力。

Because of its own characteristics of a prestressed concrete frame, when prestressed concrete frame is designed by the limit of column axial compression ratio in current common reinforced concrete codes, the column section size is usually small, an interlayer yielding mechanism wit[ form in the structure so as to suffer the severe damage under earthquake. In the other hand, excess emphasis on the limit of axial compression ratio will lead to the cost up. This paper carried out research on the yielding mechanism of prestressed concrete （PC） frames in different axial compression ratios and the effects of axial compression ratio on the seismic capacity of the PC frames designed by the current codes based on PBSD. The rationality and economy of the limited values of axial compression ratio of the PC frames were discussed. The analysis results show that an improvement of the limited values of axial compression ratio of the PC frames can ensure the seismic capacity of prestressed concrete frame under rare earthquake.