ABSTRACT

This paper presents the applicability of Reduced Length Buckling-Restrained Braces (RLBRBs) in combination with strut elements in deep excavations. Strut members are used as part of the lateral load resisting system. By proposing a new type of RLBRB section, the advantages of RLBRBs are demonstrated in dynamic soft soil-structure interactions. A numerical investigation is carried out to clarify the behavior of RLBRB-equipped strut members in supported deep diaphragm walls in soft clayey soils. The validity of the numerical models is confirmed after comparing the results of the nonlinear dynamic analyses with those of the experimental evidences. Four different excavations with 8 m, 12 m, 16 m and 20 m of clear bay spans and an excavation depth of 14 m are numerically simulated. In order to investigate the seismic analysis under various circumstances, three different accelerograms with various frequency contents are utilized. In the current study, the damping mechanism and the axial load bearing capacity of the RLBRBs in seismic conditions are taken into account in order to dissipate the induced earthquake energy and consequently preserve the local and global stability of the supported deep excavation. In this regard, one- and two-sided RLBRB-equipped struts with pipe-shaped steel cores are applied in a lateral stiffening system. As a result, unlike the conventional struts, the sudden stress changes in the struts are removed. Furthermore, the parameters influencing deep excavation stability are investigated. Basal heave, surface settlement, and lateral deformation of diaphragm walls are determined during geostatic and seismic conditions. Findings of this study provide fundamental principles for designing deep excavations under seismic conditions with efficient strut members. The applicability and effectiveness of the obtained results are also illustrated.

摘要

本文介绍了缩短长度屈曲约束支撑 (RLBRB) 与支柱元件在深基坑中的适用性。支柱构件用作侧向负载抵抗系统的一部分。通过提出一种新型的 RLBRB 截面，RLRBB 在动态软土-结构相互作用中的优势得到了体现。进行了数值研究，以阐明在软粘土中支撑的深连续墙中配备 RLBRB 的支柱构件的行为。将非线性动力学分析的结果与实验证据的结果进行比较，证实了数值模型的有效性。对 8 m、12 m、16 m 和 20 m 的净湾跨度和开挖深度为 14 m 的四种不同开挖进行了数值模拟。为了研究不同情况下的地震分析，使用了三种不同频率内容的不同加速度图。在目前的研究中，考虑到 RLBRBs 在地震条件下的阻尼机制和轴向承载能力，以消散诱发的地震能量，从而保持支撑深基坑的局部和整体稳定性。在这方面，配备管形钢芯的单侧和双侧 RLBRB 支柱应用于横向加强系统。结果，与传统支柱不同，支柱中的突然应力变化被消除。此外，还研究了影响深基坑稳定性的参数。基底隆起、地表沉降、连续墙的横向变形和横向变形是在地质静力和地震条件下确定的。这项研究的结果为在地震条件下使用高效支柱构件设计深基坑提供了基本原则。还说明了所得结果的适用性和有效性。