Experimental Evaluation of Building Response under Dynamic Loading

Abstract

Modernization in construction technology and ease of availability of newer, efficient and advance materials have led the construction of lighter and exible structures. These structures are susceptible to the dynamic loadings like Wind, earthquake etc. Therefore it is important to determine dynamic properties like Natural Frequencies, Time periods, Mode Shapes and Damping as well as dynamic response in terms of Displacement, Acceleration, Transmissibility etc. Dynamic properties of the structure can be determined analytically except Damping for which experimentation is much. Dynamic properties and response of any structure can be obtained by developing prototype of the structure and tested in well equipped dynamic testing laboratory.is evaluated excessively by experimentation conducted on real structures or their prototypes in large and well equipped laboratory. It has been found from literature that many researcher has attempted di erent types of dynamic response control techniques like Passive, Active, Hybrid etc. since excessive dynamic response may lead to severe damage to various structural elements of the structure. Mostly analytical work has been carried out to control dynamic response of structures researcher are attempting to evaluate the same experimentally. Good amount of literature is available on Passive Control of structure using Bracing, Base Isolation system, Viscous Damper, Viscoelastic Damper, Metallic Yield Damper, Friction Damper etc. In this project major objective is to determine dynamic response of structure modelled as Single Degree of Freedom (SDOF) as well as Multi Degree of Freedom (MDOF) with and without control devices like Base Isolation and Tuned Mass Damper. Firstly dynamic properties of SDOF and MDOF model are established by carrying out Free and Forced Vibration Tests with the help of Uni-axial Harmonic Shake Table, Accelerometers, Data Acquisition System, LabVIEW software and computer system. Natural Frequencies, Mode Shapes, Time Periods and Damping are evaluated for both SDOF and MDOF building models. Later, dynamic response for SDOF and MDOF building models with Base Isolation System and Tuned Mass Damper are evaluated. Dynamic response of Building Models without any Control System (i.e. uncontrolled) and with control system are compared. It has been found that value of Stifiness and Natural Frequency obtain from Experimentation and Analytically shows good agreement. Logarithmic Decrement method gives precise value of Damping than Half Power Bandwidth Method. Base Isolation has increased Damping of SDOF system to 10% from 1:15% and of MDOF system to 9:6% from 1:45% due to material property of isolators. Tuned Mass Damper has also increased Damping of SDOF system to 2:26% from 1:15% and of MDOF system to 1:9% from 1:45%. Damping of SDOF and MDOF system can further be increased by incorporating Damping parameter in the design of Tuned Mass Damper.