Engineering Commons^™

Passive Control Of Structures – The Dynamic Case, F. H. Selmani

UBT International Conference

Lately, powerful earthquakes stroke some parts of the world, while the Balkan peninsula was hit by moderate ones. During a powerful earthquake, a building structure is invaded by an enormous quantity of kinetic energy . From the manner this energy is, first absorbed, then dissipated throughout building structure depends, not only the reaction of structure as a whole, or structural elements in particular, but the nature, the distribution and the quantity of the damages also. As Nikola Tesla once quoted: “If you want to find the secrets of universe, think in terms of energy, frequency and vibration”. In order to …

Stability Of Fiber-Reinforced Bridge Bearings Under Compression And Shear Loads, Andrea Calabrese, Simone Galano, Tran Nghiem

Mineta Transportation Institute

Fiber-Reinforced Bearings (FRBs) have proven to be a valuable rubber-based base isolation technology in which flexible fiber reinforcements are used to replace the steel layers commonly adopted for the manufacturing of Laminated Rubber Bearings (LRBs). Thanks to the low weight and cost of FRBs, these devices could prove to be instrumental for the promotion of base isolation applications to houses and residential buildings of developing countries in seismic regions. This report presents the results of a large set of Finite Element Analyses (FEAs) aimed at assessing the performance of FRBs under combined axial and shear loads. The effects of different …

Effectiveness Of Seismic Base Isolation In Reinforced Concrete Multi-Storey Buildings, Ravshanbek Abdujabborovich Mavlonov, Sohiba Ergashboevna Numanova

Journal of Tashkent Institute of Railway Engineers

The dynamic reaction of a building to earthquake ground motion is the most critical reason for earthquake actuated damage to structures. The basic concept in seismic isolation is to protect the structure from the damaging effects of an earthquake by introducing a flexible support isolating the building from the shaking ground. Seismic isolation consists of essentially the installation of mechanisms such as isolators which decouple the structure from base. In the present study, the seismic response of the reinforced concrete building, base isolated by lead rubber bearings (LRBs) is compared with the seismic response of the same structure which does …

Passive Control Of Structures, Feti Selmani

UBT International Conference

Lately, powerful earthquakes stroke some parts of the world, while the Balkan Peninsula was hit by moderate ones. During a powerful earthquake, a building structure is invaded by an enormous quantity of kinetic energy . As far as the manner is concerned, this energy it is initially absorbed, and thereafter distributed throughout building structure relying not only to the reaction of structure as a whole, or structural elements in particular, but the nature, the distribution and the quantity of the damages also. As Nikola Tesla once quoted:“If you want to find the secrets of universe, think in terms of energy, …

Seismic Isolation Of A Highly Skewed, Prestressed Concrete Girder Bridge, Bradley Robson, Issam Harik, David Allen

Issam E. Harik

A relatively new approach for designing or retrofitting highway bridges in seismic zones involves isolating the superstructure from the substructure. Through experimental and analytical investigations, this study evaluates the effectiveness of isolating one particular bridge: a highly skewed, prestressed concrete, slab-on-girder bridge. Dynamic testing of the bridge was performed using the pullback, quick-release method. A three dimensional finite element model of the bridge was created. It was refined, or calibrated, to match experimentally determined natural frequencies and mode shapes. Time-history analyzes, using site-specific acceleration records, were conducted for the seismically isolated bridge model and an identical, non-isolated bridge model.

For …

Performance-Based Engineering For Evaluation And Retrofitting Non-Ductile Reinforced Concrete Buildings Incorporating Aftershock Hazard, Ruilong Han

Dissertations, Master's Theses and Master's Reports - Open

Performance-based engineering (PBE) provides a probabilistic tool for assessing the seismic risk and performance of buildings. Only the mainshock hazard has been included in the current PBE framework, although the concern on aftershock hazard has been increased recently. This study develops methodologies to incorporate aftershock hazard into a PBE framework, and assesses the seismic risk and performance of non-ductile reinforced concrete (RC) frame buildings under mainshock and aftershock hazards. A seismic retrofit strategy for these buildings, base isolation, is also evaluated using the developed methodologies.

A methodology for synthesizing aftershock ground motions is proposed and validated to resolve the challenge …

Comparative Study Of Base-Isolated And Fixed-Base Buildings Using A Damage/Cost Approach, Martin Lashgari

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

High performance base-isolated buildings are designed with a higher level of safety than the conventional fixed-base buildings under the current codes. As a sustainable development, these buildings have considerably lower social and economic impacts in a major event. The main factor limiting the extensive use of such systems is the higher initial construction costs. The cost estimations based on only initial investment may have concluded misleading results as the performance of those systems in earthquakes are different. Therefore, an evaluation considering initial costs and future repair costs due to damages from earthquakes gives a better scope for selection of an …

Seismic Performance Comparison Of A Fixed-Base Versus A Base-Isolated Office Building, Nicholas Reidar Marrs

Master's Theses

The topic of this thesis is base isolation. The purpose of this thesis is to offer a relative understanding of the seismic performance enhancements that a typical 12-story steel office building can achieve through the implementation of base isolation technology. To reach this understanding, the structures of a fixed-base office building and a base-isolated office building of similar size and layout are designed, their seismic performance is compared, and a cost-benefit analysis is completed. The base isolation system that is utilized is composed of Triple Friction Pendulum (TFP) bearings.

The work of this thesis is divided into four phases. First, …

Intelligent Controller For Smart Base Isolation Of Masonry Structures, Simon Laflamme, T.Y. Yu, Jerome J. Connor

Simon Laflamme

In this paper, an intelligent controller to control a smart base-isolated masonry structure is proposed. The smart base isolation consists of rubber bearings and a magnetorheological damper. This semi-active scheme takes advantage of the low power requirement of magnetorheological devices to achieve structural control. The controller is capable of mapping the behaviour of the controlled structure sequentially, using a self-organizing neural network which has time-varying learning rates. This neurocontroller is augmented by a sliding mode controller to account for the uncertainty on the semi-active damping forces. Wavelets are used as functions in the single hidden layer for their capability of …

Seismic Isolation Of A Highly Skewed, Prestressed Concrete Girder Bridge, Bradley Neil Robson, Issam E. Harik, David L. Allen

Kentucky Transportation Center Research Report

A relatively new approach for designing or retrofitting highway bridges in seismic zones involves isolating the superstructure from the substructure. Through experimental and analytical investigations, this study evaluates the effectiveness of isolating one particular bridge: a highly skewed, prestressed concrete, slab-on-girder bridge. Dynamic testing of the bridge was performed using the pullback, quick-release method. A three dimensional finite element model of the bridge was created. It was refined, or calibrated, to match experimentally determined natural frequencies and mode shapes. Time-history analyzes, using site-specific acceleration records, were conducted for the seismically isolated bridge model and an identical, non-isolated bridge model.

For …