···该圈梁除了起抗拉的作用外,还起要承受上部三七砖墙的压力。················································对于该圈梁,下部的受拉钢筋离受压区(上部钢筋)越远,其单位面积的钢筋所能承受的外部弯矩也越大,这样钢筋发挥效率也就越高。·····················································································如果上下部受力钢筋的位置可以占用保护层的位置,那么圈梁所能承受的力比原来的更大,钢筋效率发挥得更高······························································································。