Self-centering seismic-resistant structures: Historical overview and state-of-the-art

This state-of-the-art review provides an overview of the evolution of self-centering structures from early historical structures that inherently exhibited a recentering response to modern systems engineered for enhanced seismic resilience. From the early research investigations that were conducted since the 1960s, to the sharp increase of interest in this topic over the last two decades, self-centering seismic-resistant structures that can mitigate both damage and residual drifts following major earthquakes have seen significant advances. These systems achieve the intended self-centering response by either allowing for the rocking of primary structural elements in a controlled manner, commonly coupled with mechanical restraints and energy dissipation devices, or by including self-centering devices as main structural or supplemental structural members. To better explain the concepts and the underlying mechanics governing their seismic response, detailed schematic illustrations were developed in this article, highlighting the fundamentals behind each of these systems. This article covers a historical overview, presents the state of the research and of the art, discusses general design challenges and practical considerations, and concludes with future research needs to advance the development and broader application of self-centering systems in real structures.

Seismic Analysis of Commercial Building with Grid/Waffle slab using ETABS

In This I have studied the seismic response of various types of slab in commercial buildings and their seismic behavior is studied. As we know every year uncountable number of earthquakes occur at different places, that means, small movements of tectonic plates occur all the time causing earthquakes. A seismic resistant designed building can provide safety for more people. slabs and roofs needed more columns if we design seismic resistant design but at some places like airport, shopping mall, commercial building more column can create some problem. To overcome this problem seismic design of grid slab or waffle slabs was comes out. Grid /Waffle slab consists of Concrete beams spaced at uniform intervals in perpendicular directions which are monolithically casted with slab and they are more safe in earthquake situation as comparison of to normal conventional slab. Keywords: Grid Slab, Earthquake Load , Response Spectrum , Storey Drift, Storey Displacement , E-Tab 2018 , Base Shear, Time Period , Mode Shapes.

Rigid-Plastic Analysis of Seismic Resistant T-Frame considering Moment-Shear Interaction

To select a seismic resistant system, in addition to strength and stiffness, ductility and energy dissipation are important to be considered. Structures have nonlinear behavior under the influence of moderate and strong earthquakes. One of the primary aims in designing seismic resistant structures is to prevent the formation of undesirable collapse mechanisms such as the collapse in only a few storeys of the structure that leads to low energy dissipation. In order to achieve a global collapse mechanism, modern seismic codes provide simple rules for design, which is called the hierarchy criteria. Although these simple criteria could prevent the formation of a soft storey mechanism, they could not lead to an optimal global collapse mechanism. In these mechanisms, the energy dissipation zones include all the yielding zones such as beams, while all other parts of the structure have remained in the elastic range. TRF (T-resisting frame) is an innovative lateral resistant system introduced for architectural reasons and to provide more energy dissipating capability. This system has several collapse mechanisms due to the moment, shear, or moment-shear behavior of its members. In this paper, within the framework of the theory of plastic mechanism control, the rigid-plastic analysis of the TRF system to achieve the desired collapse mechanism is used by considering the moment-shear interaction. According to these analyses, which are performed on a single storey frame, simple hierarchy criteria are developed to create the desired collapse mechanism. Also, these criteria prevent undesired collapse mechanisms in order to have more energy dissipation and more ductility. Finally, the validity of the proposed criteria has been verified by the pushover analysis.

TREND OF SEISMIC RESPONSES OF EXISTING HIGH-RISE RC BUILDINGS

This report presents studies on the seismic response of high-rise RC buildings in Japan. Data concerning the seismic response of approximately 600 high-rise RC buildings constructed from 1972 to 2015 were collected. Seismic response characteristics were analyzed by focusing on differences in seismic resistant structures, seismic response control structures, and seismic isolation structures. The results indicated that the maximum story drift ratio response under the level 1 study seismic ground motion (R) and the level 2 study seismic ground motion (R) criteria is smaller for seismic isolation structures than that of the seismic resistant structure and seismic response control structures. In addition, focusing on the R-R relationship, the correlation is low in the seismic resistant and seismic response control structures, but is almost linear in the seismic isolation structure. This is because the seismic isolation structure is designed such that the superstructure does not become plastic even with level 2 seismic ground motion.

REINFORCEMENT METHOD OF COMPOSITE SEISMIC RESISTANT WALL BY STRUCTURAL PLYWOOD AND STEEL MEMBERS

This is a study of a composite structural wall of wood and steel, in which two steel columns are sandwiched between two plywoods with a thickness of 12 mm. Previous studies have shown that plywood undergoes out-of-plane deformation that interferes with the usability of the building. Therefore, a horizontal loading test was conducted with the position of the bolt that fastens the plywood as a parameter, and out-of-plane deformation and destructive properties were examined. Furthermore, in order to suppress out-of-plane deformation of plywood, we proposed a new reinforcement method using a steel member with a thickness of 3.2 mm. Also, its effect was verified experimentally. As a result of experiments with four types of bolt layouts, the specimen with bolt layout close to center presented small out-of-plane deformation, and each bolt layout effected the mechanical properties each other. The out-of-plane reinforcement was effective for bolt layouts that were long in the horizontal direction.