SRC-RC转换柱箍筋设置方式与破坏区域变迁

Stirrup arrangement and failure mode of SRC-RC transfer columns

通过16根SRC-RC转换柱试件和1根钢筋混凝土柱对比试件的抗震性能试验,研究了3种箍筋配置方式SRC-RC转换柱试件的屈服后变形性能和破坏特征。箍筋数量较多时,试件不但表现出超过钢筋混凝土柱的屈服后变形能力,并且变形能力的稳定性较好;箍筋数量较少时,试件的屈服后变形能力受其他构造因素影响较大。箍筋的配置对SRC-RC转换柱的破坏方式乃至破坏区域都产生了直接的影响,以通常方式配箍的SRC-RC转换柱均产生了剪切破坏,临界剪切缝贯通SRC-RC转换柱的钢筋混凝土部分。箍筋加密试件的剪切破坏区域转移到柱顶部的局部范围内。根据SRC-RC转换柱的破坏特点,提出了合理的箍筋配置方式:对于型钢延伸高度较小的试件,可对SRC-RC转换柱上部钢筋混凝土部分进行箍筋加密,而下部型钢混凝土部分则进行常规的箍筋配置。当型钢延伸高度超过3/5倍柱高时,箍筋的设置方式应能够有效控制黏结裂缝的发展,SRC-RC转换柱宜进行全高的箍筋加密。

Postpeak behavior and failure characters of SRC-RC transfer columns with different stirrup arrangements were analyzed on the basis of the experiment of 16 transfer columns and 1 reinforced concrete column under low cyclic reversed loading.When more stirrups were arranged along the height of specimens,transfer columns showed great ability and stability of deformation which were better than those of RC columns.But if stirrups were not enough,postpeak behavior of SRC-RC transfer columns was exposed to impact a lot from factors of configuration,such as section area and extension length of shape steel.Stirrup arrangement also had great influence on failure pattern.Transfer columns with stirrup setup just as RC columns suffered serious shear effect,the critical shear crack ran through the whole part of RC.Specimens with additional stirrups,no matter only at the location of shape steel discontinuity or all over the transfer column,had different failure characters.Rational manner of stirrup setup was put forward.When extension length of shape steel is not longer than 3/5 of specimen height,double mount of stirrup should be set at the RC part and normal mount at SRC part.But if extension length of shape steel exceeds 3/5 of specimen height,the double mount of stirrup from bottom to top will be proposed,which is mainly used to restrict the development of bond cracks between shape steel and concrete and promotes the cooperation of two materials.