钢管混凝土拱肋徐变研究

CREEP BEHAVIOR OF CONCRETE-FILLED STEEL TUBULAR ARCH RIB

根据钢管混凝土拱桥的特点,从变形协调条件出发,通过引入混凝土换算弹性模量,推导了钢管混凝土拱肋应力重分布计算公式。根据相似比的原则制作了钢管混凝土拱桥节段模型,在正常使用极限状态下,将试验结果与基于现行规范的计算结果比较分析证明公式正确可行,同时得出由于徐变导致混凝土承担的荷载逐渐转移为钢管承受的量值,混凝土的应力最大变化量达到52.7%,而钢管应力变化达到27.3%。并对荷载水平、含钢率和矢跨比等参数对结构长期力学性能影响规律进行研究。接着跟踪了钢管混凝土拱肋在承载能力极限状态下的徐变发展规律。

Based on the creep characteristics of concrete filled steel tubular （CFST） arch bridge, a series of stress redistribution formulae were proposed to predict the time-dependent effect on CFST arch rib by introducing the concrete transformed modulus of elasticity. A scaled segmental experimental model of CFST arch bridge was fabricated to investigate concrete creep behavior. By comparing the experimental results with the calculated ones based on the standard code under serviceability limit states, the effectiveness of this method was confirmed. It was concluded that during creep stress increased in steel tube, while decreased in concrete. The maximum stress reduction caused by concrete creep was 52.7% of the concrete initial stress, whereas the maximum stress increment in steel tube was 27.3%. Several parameters such as loading level, steel percentage and rise-span ratio were investigated to evaluate the long-term effects of CFST structures. Moreover, creep behavior of CFST arch rib under ultimate limit states was investigated.