摘要
通过对四根跨度为7.5m、预应力度不同的预应力混凝土简支梁进行长期加载,对试验梁的跨中截面徐变应变和徐变挠度进行定时观测,绘制试验梁的徐变应变系数和徐变挠度系数时程曲线,并进行对比分析。根据试验梁不同时段跨中截面不同高度处的应变徐变实测值,验证试验梁长期荷载作用下平截面假定,指出徐变作用引起截面中和轴的移动情况。以梁的徐变应变模型为研究对象,推证全预应力梁的徐变曲率系数大于徐变应变系数,部分预应力梁徐变曲率系数小于徐变应变系数,验证试验结果。推导不同预应力度的梁徐变挠度系数和徐变应变系数间的数值关系表达式,与试验结果及GB 50010—2002、JTG D62—2004等对试验梁徐变挠度系数和徐变应变系数间数值关系计算结果进行对比分析,建立考虑预应力度影响的梁徐变挠度计算公式。
Four simple supported prestressed concrete beams with a span of 7.5m and different partial prestressing ratios under long-term load were studied.The time-history curves of the strain creep coefficient and the deflection creep coefficient in the mid-span were compared.Based on the creep strain measured at different heights in mid-span section,assumption of plane section is proven for beams under long-term load.Moreover,the displacement of beam neutral axis was characterized.According to the creep strain model,the curvature creep coefficient of fully-prestressed concrete beams is greater than the strain creep coefficient,while the opposite is true for partially-prestressed beams.Furthermore,both the relational expression between the deflection creep coefficient and the strain creep coefficient and the formula considering the influence of partial prestressing ratios for calculating creep deflection were established.
出处
《土木工程学报》
EI
CSCD
北大核心
2010年第8期37-43,共7页
China Civil Engineering Journal
基金
国家自然科学基金(50574148)
河南省交通厅资助项目(2005P338)
关键词
预应力混凝土梁
预应力度
长期加载
平截面假定
徐变曲率
徐变系数
徐变挠度
prestressed concrete beam
partial prestressing ratio
long-term load
assumption of plane section
creep curvature
creep coefficient
creep deflection
