Seismic Performance of Steel Framed Building With Mass Irregularities With The Use of Different Combinations of Base Isolators and Dampers

This study addresses the nonlinear seismic responses of 3D Steel frame building upgraded with a series of passive protective systems. To this, friction damper (FD) as an energy dissipation device and lead rubber bearing (LRB), and friction pendulum bearing (FPB) base isolators are considering. For this purpose, eight different cases are taken into account. The first case contains a ten-story steel frame regular compare with irregular buildings (mass irregularities) as fixed-base (FB), the other four cases are the single use of FD, LRB and FPB in such frame, and the last three cases are the combined use of FD with LRB and FPB, Combination of isolators LRB and FPB, Combination of LRB, FPB and FD. Above same cases are considering for fifteen story steel frame regular buildings compare with irregular buildings (mass irregularities). Two ground motion records considering in this study by non-linear time history analysis in ETABS.

Effects of Soil-Structure Interaction on Torsionally Coupled Base Isolated Machine Foundation under Earthquake Load

In this paper, the influence of soil-structure interaction (SSI) on a torsionally coupled turbo-generator (TG) machine foundation is studied under earthquake ground motions. The beneficial effects of base isolators in the TG foundation under earthquake ground motions are also studied duly, considering the effects of SSI. A typical TG foundation is analyzed using a three-dimensional finite element (FE) model. Two superstructure eccentricity ratios are considered to represent the torsional coupling. Soft soil properties are considered to study the effects of SSI. This research concludes that the effects of torsional coupling alter the natural frequencies, if ignored, could lead to unsafe design. The deck accelerations and displacements are increased with an increase in superstructure eccentricity. On the other hand, the deck accelerations and displacements are greatly reduced with the help of base isolators, thus confirming the beneficial use of base isolators in machine foundations to protect the sensitive equipment from the strong earthquake ground motions. However, the effects of SSI reduce the natural frequencies of the TG foundation resting on soft soil conditions and activate the higher mode participation, resulting in amplifying the response.

SEISMIC UPGRADATION OF TALL BUILDINGS

High rises have involved interest for engineers for as long as century. All the more along these lines, the previous thirty years have seen various structures ascending starting from the earliest stage, resisting gravity. Burj Khalifa Dubai, Taipei, Petronas twin pinnacle, Empire state building are a portion of the living instances of designing wonders. What befalls a structure when it arrives at such inconceivable statures separated from the awe that it will be, it additionally represents a gigantic measure of challenge for the auxiliary architect. Since then these structures are looked by administration stacking conditions. Two destroying powers of nature, wind and seismic tremor become truly basic for these structures. The harmony among firmness and pliability to be given turns into the controlling components to the plan of such structures. Routinely giving enough firmness against colossal burdens doesn't appear to fulfill the necessities. These structures are frequently given adequate pliability so as to disperse the gigantic measure of powers. In any case, there is a limit, with respect to how much malleability can be given in a structure. A fast figuring shows that the highest-level uprooting that can be securely borne by a 500 m tall structure is nearly 2m. The structure would not fall flat if its popular narrative dislodges by 2m. Use of different sorts of dampers and isolators have been utilized in disseminating this vitality. Much exploration has gone into advancement of TMDs, ATMDs, BTMDs, and seismic base isolators. Examination has additionally gone into different kind of investigations method as more vigorous powerful examination, weakling investigation, time history investigation and execution-based investigation. Here an endeavor has been made to explore the near benefits and negative marks of various sorts of auxiliary arrangements to comprehend their conduct under seismic and wind loads. The structure considered is of 50 stories. Different designs that have been considered incorporates propped frameworks, shear divider frameworks, dampers and isolators. The investigations results have been organized and plotted to comprehend their conduct. Time history examination and execution-based investigation by sucker investigation have additionally been concentrated to comprehend the conduct of structures.