建立了核电站钢筋混凝土梁在事故工况热荷载下,极限承载状态的有限元计算模型,并将分析结果与相近实验的结果进行了对比,验证了本计算模型的正确性.考虑热约束影响,利用上述模型研究了在核电站事故工况热荷载下,钢筋混凝土梁在极限承载状态的破坏情况,以及轴力、配筋率、温度对荷载效应值的影响,并将截面热弯矩模拟值与ACI Code规范值进行了对比.分析结果表明:热弯矩随着配筋率和温度的增加而增大;ACI Code规范值对热弯矩存在高估,温度越高,规范值越偏保守.综上,提出了基于ACI Code规范的修正受弯承载力计算表达式,且表达式与各工况下的有限元结果吻合较好.
A finite element model was established to examine the ultimate state of reinforced concrete beams in nuclear power plants under accidental thermal loads. The FE model was validated by comparing the analysis results with those of published tests. Then, the validated finite element model was used to investigate the critical condition, ultimate capacity, and failure mode of the reinforced concrete beams under accidental thermal loads combined with other mechanical loads. The influence of the geometry constraint was considered, and the effects of the axial force, reinforcement ratio, and temperature on the load effect values were examined. The obtained cross-sectional thermal bending moments were compared with the ACI Code values. The results showed that the thermal moment increased with an increase in the reinforcement ratio and temperature, and the ACI Code values appeared to overestimate the thermal bending moment, particularly in the case of high temperatures. As temperature increased, the ACI Code values became more conservative. Therefore, a formula was proposed to modify the flexural capacity calculated using the ACI Code. The results based on the formula were in good agreement with the finite element results under various operating conditions.
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