木构架承重-空斗墙围护民居抗震加固振动台试验研究

Seismic retrofitted experiment on the timber frame-cavity wall houses by shaking table test

木构架承重-空斗墙围护民居大量分布在我国南方农村地区,该类民居整体性较差,历次地震中该类民居破坏较严重。采取高延性混凝土ECC面层加固围护空斗墙,扁钢、角钢及薄钢板增强木构架节点,穿墙钢筋捆绑木构架与围护墙体等加固措施。设计了1/2缩尺模型进行振动台试验,通过调整输入地震波峰值加速度来考虑不同水准地震烈度,分析了围护空斗墙损伤,探讨了模型频率与阻尼比变化特性,对比了围护空斗墙体与木构架加速度放大系数和位移包络值,并验证了二者在地震中的变形协调性。试验结果表明:(1)围护墙体仅在外侧出现明显裂缝,内侧ECC面层与墙体始终未脱离且未出现裂缝,围护墙整体性仍可得到一定保障;(2)木构架与钢加固件连接部位仅发生轻微破坏,木构架没有出现明显损伤;(3)木构架与围护墙体之间出现滑移,整体上二者协同抗震变形性能良好。该系列措施的加固效果较理想,适用于该类民居的抗震加固。

The loading bearing timber frame-enclosure cavity wall houses were largely distributed in rural areas in the south of China. This type of structure has a poor structural entirety, which had been illustrated in past earthquakes. In this study, the ECC splint was used to reinforce the enclosure cavity wall, the flat and thin steel plates were separately employed to reinforce the joints in timber frame, and reinforcing bars were adopted to improve the structural entity between cavity wall and timber frame. A 1/2 scaled structural model were constructed in order to conduct a shaking table test. The different earthquake intensities were implemented by adjustment of the peak acceleration of each earthquake ground motion. The damage of the enclosure cavity wall, the fundamental frequency and damping ratio of model were discussed. The consistencies of acceleration and displacement responses of the cavity wall and timber frame were verified, respectively. The test results showed that:(1) obvious cracks were only appeared at the outside of the enclosure cavity wall, the ECC splint was not stripped or cracked, and the integrality of the enclosure cavity wall was acceptable;(2) the connection positions between joint and member were only slightly loose and there was no obvious damage in timber frame;(3) the slippage was occurred between timber frame and cavity wall, but these two parts can still deform consistently in the loading process. The reinforcement strategy proposed in this experiment is good enough in reinforcing this kind of houses.