模板支撑薄弱层对现浇钢筋混凝土建筑结构施工荷载分布的影响

对现浇钢筋混凝土建筑结构施工期间,模板支撑系统架设中可能存在的薄弱层对施工荷载分布的影响,提出了简化分析方法,并用工程实测结果进行了验证,表明模型计算结果的正确性。分析表明,模板支撑薄弱层将导致模板支撑薄弱层的上部楼板承担的施工荷载增大,而模板支撑薄弱层下部楼板承担的施工荷载减小;实测表明,模板支撑薄弱层上的楼板承担的施工荷载同比增大约4.3%,薄弱层下的楼板承担的施工荷载减小约3.9%。施工期间应避免模板支撑薄弱层的出现,以防模板支撑薄弱层可能带来的风险。

EFFECT OF WEAKENED SHORING LAYER ON LOAD DISTRIBUTION OF REINFORCED CONCRETE STRUCTURES DURING CONSTRUCTION

Newly placed reinforced concrete structures during construction generally are supported by formwork, which transfers concrete deadweight and live loads to the placed RC floors. This temporarily load-carrying structure which consists of early-stage concrete structures and formwork is time-dependent. Its form, material property and space location all continuously vary with construction progress. In the analysis of the time-dependent structure, spacing uniformity and unchanged position of shores in upper and down level are generally assumed, but in practice there is formwork which is not consistent with that of shores in upper and down layers. This results in redistribution of construction loads between early-stage concrete slabs and shores. For analyzing the effect of weakened shoring layer on load distribution of reinforced concrete structures during construction, one simplified method is proposed, and verified by the results of engineering measurement. It is found that construction load carried by the slab above the weakened shoring layer is increased, and the construction load on the slab below the weakened shoring layer is decreased. The measurements for one high-rise concrete building during construction, indicate that the load carried by the slab above the weakened shoring layer is increased by about 4.3 percent, and the load carried by the slab below the weakened shoring layer is decreased by about 3.9 percent. Therefore, weakened shoring layer should be avoided to reduce the risk of reinforced concrete structures during construction.