ABSTRACT

The construction of low damage, self-centering, unbonded post-tensioned seismic systems requires special techniques and equipment such as hydraulic jacks to stress tendons that may not be readily available in developing communities. The recently proposed spring anchored rocking system (SARS) uses a spring at the anchorage of the post-tensioning tendon to facilitate applying force to the tendons using simple techniques such as torque wrenches. The seismic behaviour of the SARS is investigated using finite element models developed in OpenSees. The self-centering lateral force resisting system of a 3-story timber structure was anchored with springs having four different configurations, and subjected to a set of 22-pair ground motions. The finite element models consisted of elastic beam column elements to model the frame members, nonlinear truss element to model the post-tensioning tendon, spring element to model the anchorage of the tendon, and gap element to model the spring closure. It is found that the spring at the post-tensioning anchorage introduces flexibility, reduces the tendon force, and generally increases the rigid body deformations of the SARS compared to conventionally anchored systems using nuts set on bearing plates.

摘要

建造低损伤、自定心、无粘结的后张式地震系统需要特殊的技术和设备，例如液压千斤顶，以对在发展中社区可能不容易获得的肌腱施加应力。最近提出的弹簧锚定摇摆系统 (SARS) 在后张拉筋的锚固处使用弹簧，以便使用扭矩扳手等简单技术向筋施加力。使用 OpenSees 开发的有限元模型研究 SARS 的地震行为。3 层木结构的自定心抗侧力系统用四种不同配置的弹簧锚固，并承受一组 22 对地面运动。有限元模型由弹性梁柱单元组成，用于对框架构件进行建模，非线性桁架单元用于模拟后张肌腱，弹簧单元用于模拟肌腱的锚固，间隙单元用于模拟弹簧闭合。研究发现，与使用设置在轴承板上的螺母的传统锚固系统相比，后张拉锚固处的弹簧引入了柔韧性，降低了肌腱力，并且通常会增加 SARS 的刚体变形。