SEISMIC EVALUATION OF INFILLED REINFORCED CONCRETE FRAMES STRENGTHENED WITH FRPS
There is an urgent need to retrofit the deficient mid-rise reinforced concrete frame buildings in Turkey. For this purpose, an efficient FRP retrofit scheme was developed, in which hallow clay brick infill walls are utilized as lateral load resisting elements. The main premise of this practical retrofit scheme is to limit interstory deformations by FRP strengthened infill walls that are integrated to the boundary frame members through FRP anchors. Based on failure modes and measured deformation limits obtained from a large database of experiments, a diagonal compression-strut and tension-tie model is developed. The model is verified with a number of reinforced concrete frame test results with and without upgrades. Furthermore, results of a case study conducted on a typical building frame revealed that strength levels similar to that of a RC shear wall retrofit scheme can be obtained through the FRP retrofit alternative resulting in a displacement ductility of about four.
Seismic Behavior of Soft First Storey
In the aftermath of recent North Kashmir Earthquake of October 8, 2005, there is increased awareness for the need to evaluate and improve the seismic performance of multistoried reinforced concrete buildings. There are several numbers of factors affecting the behavior of building. Stiffness irregularity in vertical direction is one of them, as a result of which soft storey is formed. In the dissertation work a parametric study is performed on multistoried building with soft first storey, located in seismic zone IV. It is intended to describe the performance characteristics such as stiffness, shear force, bending moment, drift. The study is carried out on a building with the help of different mathematical models considering various methods for improving the seismic performance of the building with soft first storey. Analytical models represent all existing components that influence the mass, strength, stiffness and deformability of structure. The equivalent static and multimodal dynamic analysis is carried out on the entire mathematical 3D model using the software SAP2000 and the comparisons of these models are presented. Finally, the performance of all the building models is observed in high seismic zone V. Keywords: Soft storey, Problem, Parametric study, Earthquake Analysis, IS 1893:2002 provisions.
Exponential stabilization of an axially moving string with geometrical nonlinearity by linear boundary feedback
This paper addresses the vibration suppression problem of an axially moving string using boundary control. Taking into account large transverse motion of the string via the second-order component of Lagrangian strain, a nonlinear oscillation equation is derived for the problem by employing the Hamilton's Principle. Direct Lyapunov method is then adopted to demonstrate that a linear boundary control of negative speed feedback ensures the vibration response of the moving string exponentially stable. The main contributions are a new stability condition in terms of controller gain parameter, and a detailed demonstration on the equilibrium condition at the boundary where the control is applied.