论文部分内容阅读
针对足尺有粘结预应力混凝土梁板高温后的抗弯承栽力开展了非线性计算分析。结果表明,综合配筋指标、有效预应力对高温后极限弯矩与常温下极限弯矩比值M_u~A/M_u的影响不大,预应力度和预应力筋的保护层厚度对M_u~A/M_u影响显著。高宽比近似相同的有粘结预应力混凝土梁,当第一排钢筋的保护层厚度相同时,受火时间为3 h,高度为700 mm的梁高温后截面承栽力下降幅度最大约为30%,高度为4500 mm的梁高温后截面承栽力下降幅度不到10%,高温后大尺度梁的力学性能优于小尺度梁。给出了考虑预应力筋保护层厚度和预应力度影响的有粘结预应力混凝土板M_u~A/M_u的计算公式,以及综合考虑预应力筋、非预应力筋合力点到梁底距离和预应力筋梁侧保护层厚度影响的有粘结预应力混凝土梁M_u~A/M_u的计算公式。
The nonlinear calculation and analysis are carried out for the flexural bearing capacity of full-scale prestressed concrete beams after bonding at high temperature. The results show that the comprehensive reinforcement index and effective prestress have little effect on the ultimate bending moment ratio M_u ~ A / M_u at room temperature. The thickness of prestressed and prestressed tendons has a significant effect on the M_u ~ A / M_u significant impact. When the thickness of the protective layer of the first row of steel bars is the same, the maximum decrease of the bearing capacity of the cross section of the girder subjected to the high temperature of 3 mm and the height of 700 mm is about After 30 ℃, the height of the beam is 4500 mm, the bearing capacity of the cross-section decreases less than 10%, and the mechanical properties of the large-scale beam are better than that of the small-size beam after the high temperature. The formulas for calculating M_u ~ A / M_u of bonded prestressed concrete slabs considering the thickness of prestressing tendons and the influence of prestressing strength are given, and the formulas of M_u ~ A / Calculation formula of M_u ~ A / M_u for bonded prestressed concrete beams affected by the thickness of prestressed tendons and side protection.