Describes currently used seismic isolation systems in detail. Evaluates the performance of seismically isolated structures and provides examples of their response under earthquake action. Proposes a preliminary design methodology for seismically isolated structures. Accessible to both students and practising structural engineers who need to familiarise themselves with this approach. These authors present much sought after information on the design procedures for seismically isolated structures.
Using a logical progression, they describe seismic isolation along with the concepts of earthquake structural dynamics underlying the isolation theory. Methods discussed will provide the basis for continuing development and refinement. Seismic isolation offers the highest degree of earthquake protection to buildings and their inhabitants. Modern applications of the technology are less than 50 years old and uptake in seismically active regions continues to soar.
Seismic Isolation for Architects is a comprehensive introduction to the theory and practice in this field. The book is written for an international audience: the authors review codes and practices from a number of countries and draw on examples from eleven territories including the US, Chile, Argentina, Italy, Japan, and New Zealand.
Aimed at readers without prior knowledge of structural engineering, the book provides an accessible, non-technical approach without using equations or calculations, instead using over drawings, diagrams and images to support the text.
This book is key reading for students on architecture and civil engineering courses looking for a clear introduction to seismic-resistant design, as well as architects and engineers working in seismically active regions. Seismic isolation offers a simple and direct opportunity to control or even eliminate damage to structures subjected to ground shaking by simultaneously reducing deformations and acceleration demands.
A base isolation system decouples the superstructure from the ground resulting in elongation of fundamental period of the structure and reducing the accelerations transferred to superstructure during ground shaking.
However, increasing the fundamental period of the structure is mostly accompanied by increased displacement demands. In base isolated structures, this large displacement is concentrated at base level where seismic isolation devices are installed and designed to handle these large deformations without damage. A typical base isolated basement design requires a space in which the building is free to move sideways without hitting the surrounding structure.
This space is commonly referred to as the "moat". Structural design codes such as ASCE that regulate the design of buildings incorporating seismic base isolation systems require the minimum moat wall clearance distance equal to the maximum displacement at the base of the structure under the Maximum Considered Earthquake MCE , although the superstructure is designed for design basis earthquake DBE level.
Despite the cautious regulation for moat wall gap distance, pounding of base isolated buildings to moat walls has been reported in previous earthquakes. In conventional structures, the pounding problem between adjacent structures of buildings and highway bridges has been a major cause of seismic damage, even collapse, during earthquakes in the past several decades. Current design specifications may not adequately account for the large forces generated during impact in base isolated buildings.
This study investigates the pounding phenomenon in base isolated buildings from both experimental and analytical perspectives by conducting shake table pounding experiments, developing effective models for impact to moat walls and evaluating the adequacy of code specifications for the gap distance of moat walls.
A series of prototype base isolated moment and braced buildings designed by professional engineers for the purpose of this project is presented and one of the models was selected for a quarter scale shake table test with moat walls. The pounding experiments indicate that the contact forces generated during pounding can induce yielding in the superstructure and amplify the response acceleration at all stories of the building.
The response amplification and damage depends on the gap distance, moat wall properties, and impact velocity. A detailed finite element model of the test setup is developed in OpenSees.
An analytical study on the dynamic behavior of the moat walls resulted in proposing a new impact element. Numerical simulation using the proposed impact element compares well with experimental results. A series of collapse studies using the Methodology in FEMA P was conducted for both prototype models at various gap distances.
The collapse probability of base isolated models used in this study and the effect of moat wall gap distance on the probability of collapse for base isolated structures is investigated. These studies verify that pounding to moat walls at the required gap distance by ASCE result in acceptable probability of collapse for the flexible and ductile moment frame models examined. Paul Guyer, P. Introductory technical guidance for civil and structural engineers interested in seismic isolation and energy dissipation systems for buildings.
This is achieved by suggested separating the structure from the foundation by a mounting the structures on a set of isolators that provides low layer of talc; isolation system reduces accelerations in the horizontal stiffness and consequently, shifts the fundamental isolated building at the expense of large relative displacements frequencies of the structures to much lower values.
A between the building and the foundation. In the base isolation strategy, it is possible to obtain a considerable reduction of large displacements attained at the base level as a consequence of the energy dissipation due to damping and hysteretic properties of isolation device.
Many buildings have been constructed on various types of seismic bearings, and such structures have shown superior performance during earthquakes [1]. This is the first seismically isolated i. With The advantage claimed in this type of bearing is that the this technology, the building can sway for 35 cm in the two unnecessary movement of the structure under low load levels horizontal directions for an earthquake measuring eight on the due to wind and low intensity earthquake is prevented on Richter scale.
At higher loads, the plug yields and the shear stiffness of the system is 2. Through the horizontal components of the ground motion by imposing high energy dissipation capacity, it is possible to reduce the structural elements with low horizontal stiffness between the horizontal displacement, in comparison with that of an structure and foundation. The superstructure essentially acts isolation system with the same equivalent stiffness but lower like a rigid body with reduced inter storey drifts, thus energy dissipation capacity.
Usually, they are circular in shape mitigating the subsequent seismic damage. The fabricated with more than one lead core. Also, it brings additional damping due to Isolators the increased damping introduced at the base level, and thus The total horizontal and vertical stiffness of the rubber further reduction in the spectral acceleration is achieved.
Area of Lead AP Q Steel plate thickness tS 2 0. Response spectra for 5 percent damping IS are shown in Fig. The selected building was designed for seismic loads as per IS Part 1 : [7]. This book is key reading for students on architecture and civil engineering courses looking for a clear introduction to seismic-resistant design, as well as architects and engineers working in seismically active regions. A structural engineer with many years' earthquake engineering experience, he now teaches Structures.
She is in the process of completing her doctoral thesis on 'Architecture and Base Isolation'.
0コメント