预应力混凝土梁开裂刚度退化及张拉力优化研究

打开文本图片集

Study on the Degradation of Cracking Stiffness of Prestressed Concrete Beams and the Optimization ofPrestressing Force

MA Zhaohua CHEN Shunchao KANG Peng WANG Ruipeng TANG Longsheng （School of Civil Engineering，Southwest Forestry University，Kunming 65O224，China）

Abstract： [Purposes] Although prestressing technology significantly improves the crack resistance of concrete beams，the nonlinear response mechanism of stiffness degradation after cracking remains unclear，particularly lacking a quantitative understanding of the diminishing marginal effect between prestresing force levels and stiffness improvement.[Methods] Two rectangular prestressed concrete beams were designed toanalyze thedeflection，strain，and short-termstiffness characteristicsunder prestressing forces of 60，1O0，and 150 kN.[Findings] Prestressing effctively restrains crack propagationand enhances stiffness，but the improvement effect of stress increments on stiffness significantly weakens with increasing prestressing force.[Conclusions] Based on experimental data，it is recommended to control the prestressng force within the range of 1O0～130 kN in practical engineering.The research findings provide experimental evidenceand a theoretical optimization basis for the prestressed reinforcement design of cracked concrete beams.

Keywords： prestressed concrete beams; prestressing force; stiffess degradation; crack propagation; law of diminishing marginal returns

0 引言

混凝土梁作为现代建筑及桥梁工程建设中的主要受力构件之一，其抗弯承载力的精确计算对结构安全及性能有着直接影响。（剩余6328字）