折线先张法预应力混凝土梁长期变形试验研究

Experimental study on long-term deformation of prestressed concrete beams with pretensioned bent-up tendons

通过对两根置于室内近似标准环境、一根置于室外自然环境中的长7.5 m折线先张法预应力混凝土梁长期加载,对跨中挠度进行了600 d的量测,绘制了跨中长期挠度及长期挠度系数时程曲线,对其影响因素进行分析。采用Datafit软件对长期挠度系数时程规律进行了数值分析,建立了以混凝土徐变"先天理论"为基础的长期挠度系数工程实用表达式。对该公式进行了精度分析表明误差在±10%以内,并指出了其该类梁长期挠度增大系数终值ηθ可取为2.15,可供折线先张法预应力混凝土梁进行长期挠度预测时参考。

By observing deformation of three simple supported prestressed concrete beams under long-term loading about 600 d,whose span were 7.5 m and equiped with pretensioned bent-up tendons,also two of them were put in standard indoor curing environment and the other one was put outdoor,the long-term deflection in different time was obtained and the time-history curves of long-term deflection coefficient in midspan section were plot.Utilizing Datafit software,long-term deflection coefficient equation of the test beams was fitted,and the equation model of long-term deflection coefficient was put forward,which was based on ＂geneogenous theory＂about concrete creep.Moreover,the end value of long-term deflection coefficient η θ could be considered to be 2.15.