基于抗裂要求的楼面梁预应力筋数量及其影响因素探讨

在房屋建筑结构的楼面预应力梁设计中,一般需要先行估算预应力筋的数量,传统的基于经验的估算方法往往误差较大.对满足各级抗裂要求所需的预应力筋数量进行了研究.首先列出3种抗裂等级所对应的预应力筋数量的表达公式,引入合理假定后,得到预应力梁跨中和支座处所需预应力筋数量的简化计算公式.之后对预应力筋数量的各种影响因素(梁截面形状、梁跨度、梁截面宽度、抗裂等级、板厚、预应力筋位置等)分别进行了讨论,得出了预应力筋数量与各因素的关系曲线,再将各因素对预应力筋数量的影响程度进行了比较,为结构设计人员在初步设计阶段估算预应力筋数量提供了一种较为准确的依据.

Discussion on the Number of Prestressed Tendons in Building Floor Beams and Its Influential Factors Based on Crack Resistance Requirement

In the design of prestressed beams in building structures,the prediction of the number of prestreesed tendons is necessary.The tendon number meeting the demands of crack resistance was studied.The formulas for calculating the number of prestressed tendons under three crack resistance grades were listed.By introducing reasonable assumptions,the simplified calculation formulas for determining the tendon number at the mid-span and support point were provided.The various influential factors of the tendon number,e.g.,the beam section shape,span of the beam,section width,crack resistance grade,slab thickness and position of prestressed tendons were discussed respectively.The relationship curves between the number and various influenctial factors were presented.The impact extent of various factors on the number was compared.A relatively accurate basis for estimating the number of prestressed tendons in the primary design phase was provided for structural designers.