预应力组合梁的弹性性能分析

Elastic behavior analysis of prestressed composite beam

预应力钢-混凝土梁已应用于各种结构工程及对现有结构的加固中.采用简化分析方法研究了梁的弹性性能.即采用换算面积法,把混凝土面积转换为等效的钢面积进行计算,可得到弹性范围内简支梁的应力、应变及屈服荷载.实例计算结果表明,预应力组合梁的屈服荷载比普通组合梁的屈服荷载高,组合梁的弹性工作范围扩大了;对组合梁施加预应力后,可以减小弹性范围内的最大挠度,增强梁的刚度;在跨中集中荷载作用下,直线布置方案比三角形布置方案可产生更大的反拱,最大挠度减少近14%.

Prestressed steel-reinforced concrete beams have been used in the fields of structural engineering and strengthening of existing buildings. In this paper, elastic behavior of composite beams is investigated by simplified analysis method, which is used to transform the reinforced concrete area into an equivalent steel area. Then the stresses, strains and yield load of beams which behave elastically are obtained. The results of this investigation show that the yield load of prestressed composite beams is higher than that of reinforced concrete composite ones, which widen the elastic area they behaved. After having been prestressed, the composite beams can reduce the maximum flexibility within the range of elasticity, and increase their stiffness. Under the concentrated load located on the middle of the span, there is larger contraflexure when the shape of the wires is linear, with higher yield load and less maximum flexibility compared with that of triangular shape.