双筋矩形截面梁经济配筋条件分析

Analysis of Economical Bar Arrangement Condition for Double Reinforcement Rectangle Section RC Beam

在设计钢筋混凝土双筋矩形截面梁时,受拉钢筋As、受压钢筋A′s均未知,考虑到充分利用混凝土的抗压能力,使钢筋As和A′s总的用量最少,取ξ=ξb.对该条件的公式进行了推导;分析了破坏时梁截面的应力应变情况.适当提高受压钢筋配筋率,并不会使总配筋量增加太多.算例表明,当受压钢筋配筋率增加37 6%时,总配筋率仅增加6 6%.

In the designment of double reinforcement rectangle section RC beam , the condition of tension reinforcement and compression bar is unknown, 'ξ=ξ_b' is regarded as supplementary condition(economical bar arrangement condition). The concrete′s ability of renitency is fully used.The total use of steel is the most economical . Analysis is introduced about the supplementary condition from deducing formula and the stress-strain change of beam′s section when it is destroyed.The total use of steel can′t be increased too much though the use of reinforcement which is disposed in the RC beam′s compressive region is increased properly. It is shown that the ratio of reinforcement which are disposed in the RC beam′s compressive region is increased to 37.6%, the total ratio of reinforcement is only increased to 6.6%.