International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | Mar -2017
p-ISSN: 2395-0072
www.irjet.net
EVALUATION OF RESPONSE REDUCTION FACTOR FOR MOMENT RESISTING STEEL FRAMES- A REVIEW Aswathy Swaminathan 1 , Prof. Asha Varma P 2 1PG
Student , Dept . Of Civil Engineering , NSS College Of Engineering , Palakkad , India
2Professor
, Dept . Of Civil Engineering , NSS College Of Engineering , Palakkad , India
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Abstract - Moment resisting frames are an assemblage of columns and beams that are rigidly connected thus providing sufficient strength and lateral stiffness. They are commonly used a dominant model of lateral resistance system in seismic regions. Damage levels of buildings structures under a design Earthquake are closely related to certain assigned values of response reduction factor. The poor performance of Ordinary Moment Resisting Frame (OMRF) in past earthquakes suggested special design and detailing to warrant a ductile behaviour in seismic zones of high earthquakes. So when a large earthquake occurs, Special Moment Resisting Frame (SMRF) which is specially detailed with a response reduction factor is expected to have superior ductility. The objective of my study is to evaluate the response reduction factors for steel frames through a non linear modeling. The purpose of study in steel frames is that steel has ability to undergo seismic excitation. In this study steel framing systems are investigated and seismic response modification factors of individual systems are analyzed. Numerous load resisting layouts, such as different bracing systems and unbraced moment resisting frames with various bay and story configurations are designed and evaluated in a parametric fashion. The structure is analysed in SAP2000 and the R values so obtained from the analysis is compared with codal requirements considering the various areas of seismicity and different sets of ground motion of various intensities and frequencies. Method of analysis, design and evaluation data are presented in detail. Previous studies in literature and the theory of response reduction factor is also presented.
structures which were designed and built according to the actual seismic codes were subjected to strong ground motions, exceeding the levels for which they were designed. A great number of high and mid rise buildings have steel moment resisting frames on primary lateral load resisting system. This type of construction was considered the safest one to be able to sustain large plastic deformation in bending and shear. In general it can be stated that the behavior of steel buildings during such earthquakes was satisfactory. However, damage with local failures in the steel elements or in the beam-to-column joints was observed. This proves that steel structures are vulnerable to seismic excitation and the importance of improving design rules for buildings in seismic zones was evident. These rules should take into account the real structural behaviour, the ductility demand under cyclic loading and damage due to the plastic deformation that should not exceed limits related to the local and global ductility of the structure. Although steel structures, performed well during recent earthquakes from a life safety perspective ,economic loss and business interruptions were high .Hence, damage control has become more important, particularly when the performance based seismic design philosophy was developed. This is a general philosophy in which design criteria and structural systems are chosen on the basis of a specified level of reliability so that the structure will not be damaged beyond certain limits. Some recent seismic design codes are based on force-controlled design or capacity design. In order to develop simple design rules for steel structures in seismic zones it is important to characterize the behaviour of steel members and beam-to-column joints under cyclic reversal loading, and to focus on the damage caused by plastic deformations and low cycle fatigue. Theoretically, when considered at a material level steel can develop a large ductility as obtainable by a tensile test but in practice, the global inelastic behaviour of steel structures , local buckling and low-cycle fatigue influences both in the steel members and their connections
Key Words: response modification factors, steel frames, nonlinear static analysis, seismic performance. 1.INTRODUCTION There are many natural hazards in the world but earthquakes are one of the most destructive natural hazards that can result is severe social and economic impact. The devastating potential of an earthquake can have major consequences on infrastructures and lifelines. During the last two decades, some devastating earthquakes have occurred throughout the world .A large number of
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