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进行了3根预应力轴心受拉钢构件高温试验研究。试验结果表明,高温下预应力轴心受拉构件中内置拉索和钢管所承受荷载比例随温度的变化而不断变化。升温初期拉索张力随温度升高不断增大,预应力轴心受拉钢构件轴向位移平稳发展,在达到峰值后,拉索张力随升温时间的延长而不断降低。在临界状态下,轴向位移增长很快,预应力受拉构件中拉索均被拉断,外部钢管发生不同程度的颈缩现象。在试验结果的基础上,建立了预应力轴心受拉钢构件的有限元分析模型,得到了高温作用下预应力轴心拉杆中拉索张力和预应力钢杆轴向位移的时程全曲线。参数分析的结果表明:在其他条件相同时,预应力轴心受拉钢构件失效时的临界温度随着荷载比的增加而降低;当预应力比小于0.8时,预应力比对预应力轴心受拉钢构件失效时的临界温度的影响较小,当预应力比等于0.8时,预应力轴心受拉钢构件失效时的临界温度显著的提高;在其他条件相同时,预应力轴心受拉钢构件失效的临界温度随约束刚度比的增大而增大。最后对高温下预应力轴心受拉钢构件进行了理论分析,推导出预应力轴心受拉钢构件高温下差分计算方法,并以此为基础编写程序。通过计算结果与试验结果的对比,证明了差分计算方法的正确性。
Three prestressed axial tensioned steel members were tested at high temperature. The experimental results show that the load ratio of the built-in cables and steel tubes in the prestressed axial tension members at high temperature varies with temperature. In the early stage of heating, the tension of the cable increases with increasing temperature, and the prestressed axial center develops smoothly by the axial displacement of the steel members. After reaching the peak value, the tension of the cable decreases with the extension of the heating time. In the critical condition, the axial displacement increases rapidly, and the cables in the prestressed tension members are pulled off, and the outer pipe undergoes different degrees of necking. Based on the experimental results, the finite element model of the prestressed axially tensioned steel member was established, and the full-time curve of the prestressed axial tensioned prestressed steel rod and the axial displacement of the prestressed axial rod . The results of parametric analysis show that the critical temperature of the prestressed axial core under the same failure condition decreases with the increase of the load ratio under the same conditions. When the prestressed ratio is less than 0.8, When the prestress ratio is equal to 0.8, the critical temperature at the failure of the prestressed axial core is significantly increased. When the other conditions are the same, the prestressed axial center is affected by The critical temperature at failure of steel members increases with the restraining stiffness ratio. Finally, the theoretical analysis of tensioned steel members at prestressed axial center under high temperature was deduced, and the differential calculation method of prestressed axial tensioned steel members at high temperature was deduced. Based on this, the program was programmed. By comparing the calculation results with the experimental results, the correctness of the difference calculation method is proved.