折纸型支撑在装配整体式框架中的耗能和屈曲控制机制研究

装配整体式混凝土框架结构在地震作用下通常会产生较大侧移且残余变形明显，设置中心支撑是增大其抗侧刚度的常用做法，但支撑在受压时容易发生整体弯曲屈曲而失稳，进而显著削弱其在地震作用下的耗能能力。本项目将变角度Miura折纸构形运用于较长管状构件上以延迟其受压屈曲失稳的发生，形成基于变角度Miura折纸的折纸型屈曲控制支撑，并拟针对两类顶点对基于变角度Miura折纸管状构件轴向变形能力的影响机制、新型支撑在低周往复荷载作用下的屈曲控制机制等关键科学问题展开理论和试验研究。首先，通过空间几何关系推导，形成新型支撑几何设计通用方法，并构建合理的折痕分配方案运用于支撑上。然后，通过支撑和带支撑的装配整体式框架子结构低周往复试验，揭示支撑在地震作用下和框架共同工作时的受力机理、耗能机制和失效模式。最后，形成新型支撑及其带支撑框架的设计方法和建议。本项目的实施将为解决中心支撑受压失稳问题提供一种新思路。

Monolithic precast concrete frames usually suffer large lateral drift and apparent residual deformation under earthquake actions. Concentric braces are commonly used to increase the lateral stiffness, but the majority of the braces tend to experience instability due to global flexural buckling, thereby severely degrading the energy dissipation capacity under earthquake actions. This project develops an innovative Miura origami-based buckling-controlled brace (MOBBCB) by applying properly-designed curved Miura origami pattern to longer tubes for buckling delay. Theoretic and experimental study are conducted to address scientific issues such as the effect of two types of vertices on the deformation capacity of curved Miura origami-based tubes and buckling control mechanism of the brace under reversed cyclic load. Firstly, the universal geometrical design approach of the brace is formed by mathematical derivations via spatial geometrical relationships, and a rational fold-line scheme is established and applied to the brace. Then, uniaxial brace test and sub-assemblage test are conducted to reveal load bearing mechanism, energy dissipation pattern and failure mode of the brace when working together with the surrounding frame under earthquake actions. Lastly, design method and suggestions for the brace and the frame are given. The implementation of the project provides an alternative solution to the instability issue of concentric braces.