Book Details : | |
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Language | English |

Pages | 307 |

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Size | 25.86 MB |

Earthquake Resistant Design of Buildings by Mehmet E. Uz and Muhammad N.S. Hadi | PDF Free Download.

- Effects of Earthquake on Structures
- Mathematical Modelling of Adjacent Buildings under Earthquake
- Seismic Isolation and Energy-dissipating Devices
- Algorithms for Designing Optimal Control Force
- Genetic Algorithms for Single and Multi-Objective Optimisation
- Verification of the Approximate and Rigorous Models for Adjacent
- Case Studies
- Results in Frequency and Time Domains
- Results for Optimum Placement of Dampers
- Optimum Design Examples
- Results and Discussion
- Summary and Conclusions

While introducing important concepts in the study of earthquakes related to retrofitting of structures to be made earthquake resistant.

The book investigates the pounding effects on base-isolated buildings, the soil-structure-interaction effects on adjacent buildings due to the impact, the seismic protection of adjacent buildings, and the mitigation of earthquake-induced vibrations of two adjacent structures.

These concepts call for a new understanding of controlled systems with passive-active dampers and semi-active dampers.

The passive control strategy of coupled buildings is investigated for seismic protection in comparison to active and semi-active control strategies.

In the context of structural design, optimization is essential to create structural systems that maximize the levels of safety and economize on the limited resources available in computerized structural design methods.

Residential buildings, which are located in seismically active regions, are often built close to each other due to the economics of land use or architectural reasons.

Pounding refers to a building hitting an adjacent building due to lateral loading, for example, an earthquake, which is one of the main causes of severe building damages. Non-structural damage means movement across separation joints between adjacent buildings.

Due to the closeness of structures, the pounding problem is especially widespread and dangerous since maximum land use is required. The simplest way to reduce or avoid pounding is to provide adequate separation distance between the buildings.

The required separation distance is not always easy to provide. Thus, a minimum separation distance is desired between adjacent buildings. This book describes a range of pounding reduction devices and a comprehensive literature review of topics that form the background.

The problem is complicated by the fact that adjacent buildings with different owners are built at different times with different building code specifications. These buildings can be designed with different dynamic characteristics.

Seismic pounding between adjacent buildings with different dynamic characteristics can occur because of the lack of an essential gap between the buildings.

Further, the book shows the effect of the use of dampers on the dynamic characteristics of the building models, with respect to shear wave velocity on the soil-structure interaction (SSI) systems, the available modal analysis methods for SSI systems, and their application to Multi Degree Of Freedom (MDOF) modal response history analyses.

The main differences and advantages are pointed out in addition to the optimal design of passive, active, and semiactive devices in structural control optimization and design approaches.

Investigation of both the pounding response, including soil-structure interaction (SSI) and pounding of seismically isolated buildings, without considering the presence of adjacent buildings is very limited.

By considering the recent developments in the structural control methods, the concept of a control system for adjacent buildings plays an important role. Thus, this book develops a methodological framework that is applicable to various types of structural engineering projects.

These projects can be a design and/or retrofit of structures with some control devices in the scope of structural optimization problems.

In addition, according to a certain performance index, the designed control system needs to be optimum in some sense.

Optimum dampers, parameters of passive control devices, command voltage of semi-active dampers, and stable controllers of active control systems are obtained according to the chosen performance index.

Some assumptions have been adopted during the calculations for highlighting the important features of damper devices connected to neighboring buildings and investigating the effect of soil-structure interaction on the response of fixed-base isolated buildings.

The rigid diaphragm of the floor is assumed. A linear multi-degree of freedom system where the mass of each level is lumped in the floors is provided for each building.

The stiffness is provided in terms of columns. Moreover, the friction coefficients between the sliding surfaces are taken as constant while the base-isolated buildings are investigated.

The spatial difference of the ground motion can be neglected because the total plan dimensions of the buildings in the excitation direction are not large. Pounding forces are calculated by the Coulomb friction model.

Hence, in the planer and z vertical directions, the coefficient of friction and coefficient of restitution for energy dissipation is assumed to be constant during the impact.

The SSI forces are modeled in the form of frequency-independent soil springs and dashpots with modeling the coupled buildings resting on the surface of an elastic halfspace.

An investigation is carried out in three parts for the specific objectives of this book. Firstly, the investigation is done to analyze the earthquake-induced pounding between two insufficiently separated buildings, considering the inelastic behavior of the structures’ response.

Secondly, the seismic response history analysis of multi-story inelastic adjacent buildings of different sizes with SSI systems during the impact is investigated.

After the first two parts, the specific objectives of this book continue to focus on the reduction of displacement, acceleration, and sheer force responses of adjacent buildings, using supplemental damping devices.

Further, the optimal placement of the damper devices, instead of placing them on all the floors in order to minimize the cost of the dampers, is investigated. Various earthquake records are used to examine the seismic response of two buildings under different ground motions.

A formulation of the equation of motion for two different buildings is presented for each numerical example used in this book.

The resulting systems of second-order constant-coefficient equations are reformulated as a system of first-order ordinary differential equations and solved, using the ordinary differential equation solver of MATLAB.

The coupled multi-degrees of freedom modal differential equations of motion for two-way asymmetric shear buildings are derived and solved, using a step-by-step solution by the fourth-order Runge-Kutta method with and without any impact in this book.

A conventional optimization approach is combined with multiple objective functions into a single-objective function by use of arbitrary weights.

The three objectives of this book are to minimize the number of MR dampers for economical benefits, the H∞ norm transfer function from external disturbance to the regulated output, and the peak displacement or story drift responses non-dimensionalized by related responses of the uncontrolled system.

Numerical results of adjacent buildings controlled with MR dampers and the corresponding uncontrolled results are examined and compared with non-linear control algorithms. The optimal design of semi-active dampers placed between adjacent buildings is investigated in two different parts.

The binary-coded GA automatically employs and optimizes the controllers used in this book in accordance with the fitness function that reflects the multi-objective.

In the first part, an adaptive method for the design of a Fuzzy Logic Control (FLC) system for protecting adjacent buildings under dynamic hazards using MR dampers is proposed in a single GA.

The design of the Genetic Adaptive Fuzzy (GAF) controller is conducted in the first part of this book. Minimizations of the peak interstorey drift and displacement related to ground responses are the two objectives.

A global optimization method which is a modification of the binary-coded genetic algorithm adopted by Arfiadi and Hadi (2000, 2001) is used. Binary coded GA is used to derive an adaptive method for the selection of fuzzy rules of the FLC system.

The fuzzy correlation between the inputs (structural responses) and the outputs (command voltages) of the controller is provided by adding, changing, and deleting the rules of the FLC system. Inputs are taken as top-floor displacements of both the buildings.

Nevertheless, the multi objectives combined with a single genetic algorithm and NSGA-II are also directly used as controllers to determine the vectors of both the number of dampers and the command voltage for each floor.

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