Despite good rigidity, braced frames have weak nonlinear behavior and inadequate distribution of ductility in stories, which cause significant structural damage. In this research, a seismic resistant system called coupled concentrically braced frame (CCBF) is developed to enhance the performance of braced frames by coupling them with a beam. In this case, the coupling beams are the primary source for ductility of the system, and after their yielding in more severe earthquakes, the structure continues to benefit from the ductility of the braces as the secondary source; therefore, the system has two-level behavior caused by different probable seismic excitations. In this case, in addition to maintaining the stiffness of the two concentrically braced frames, the coupling beams resist against the movement of the braced frames, and as a result, the stiffness of the system is increased. Therefore, lighter elements can be used to resist lateral loads. Linear and nonlinear analyses of CCBF, and its comparison with other braced frames, indicate that participation of the coupling beams provides an adequate stiffness and ductility. These frames have more stable nonlinear behavior than conventional ones and continue their nonlinear behavior even after fracture of coupling beams in severe earthquakes.

中文翻译：

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多层次增强地面连梁支撑系统的结构性能

尽管刚性良好，但支撑框架的非线性行为较弱且楼层延展性分布不充分，从而导致严重的结构损坏。在这项研究中，开发了一种称为耦合同心支撑框架（CCBF）的抗震系统，通过将支撑框架与梁耦合来增强支撑框架的性能。在这种情况下，连梁是系统延性的主要来源，在更严重的地震中屈服后，结构继续受益于支撑的延性作为次要来源；因此，系统具有由不同可能的地震激励引起的两级行为。在这种情况下，除了保持两个同心支撑框架的刚度外，连梁还抵抗支撑框架的移动，从而增加了系统的刚度。因此，可以使用较轻的元件来抵抗横向载荷。CCBF 的线性和非线性分析及其与其他支撑框架的比较表明，连梁的参与提供了足够的刚度和延展性。这些框架比传统框架具有更稳定的非线性行为，并且即使在严重地震中连梁断裂后也能继续其非线性行为。