MEASUREMENT AND ANALYSIS OF EARLY-AGE CAMBER OF PRESTRESSED CONCRETE DOUBLETEES
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摘要: 对3根混凝土强度等级为C50的双T板构件进行了预应力放张反拱以及7 d反拱实测,并测试了与构件同材料且同条件养护混凝土试块的弹性模量和抗压强度。结果表明:蒸汽养护龄期30 h和自然养护龄期3 d时,混凝土抗压强度可达设计混凝土强度等级值的80%,但混凝土弹性模量仅为规范值的38%~55%;龄期7 d的混凝土弹性模量则可达到规范值;蒸汽养护试块的混凝土抗压强度和弹性模量相对自然养护试块发展更快。利用实测数据,回归分析得到了7 d内的混凝土弹性模量时效模型,并采用规范MC 2010收缩徐变模型,对构件7 d反拱值进行了估算,计算值与实测值符合较好。Abstract: The cambers of three prestressed concrete doubletees with concrete strength grade of C50 at the moment of prestressed tendons releasing and the age of 7 days were measured, meanwhile, the elastic modulus and compressive strength of the concrete specimens with the same material and curing condition were tested. The result showed that when steam curing for 30 hours or natural curing for 3 days, the compressive strength of the concrete could reach 80% of the designed concrete strength grade value, but the elastic modulus of the concrete only reached 38~55% of the standard value. The elastic modulus of the tested concrete with an age of 7 days could reach its standard value. Compared to natural-cured concrete, the compressive strength and elastic modulus of steam-cured concrete developed more rapidly. The time-effect model of concrete elastic modulus within the age of 7 days was obtained by regression analysis. Then a simulation analysis of the cambers at the age of 7 days was carried out based on the model of creep and shrinkage in MC 2010, and the calculated values were almost coincident with the measured values.
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