IJSRD - International Journal for Scientific Research & Development| Vol. 4, Issue 03, 2016 | ISSN (online): 2321-0613 All rights reserved by www.ijsrd.com 867 Effect of Different Foundation Systems on Response Reduction Factor of R.C.C Frame Type Staging using Non-Linear Static Push-Over Analysis Gajera Jatin H 1 Prof. Modi Poonam I 2 Pancholi Vasu V 3 1 P.G. Student 2 Assistant Professor 3 Senior Geologist 1,2 L.D. College of engineering, Ahmedabad 3 Institute of Seismological Research, Gandhinagar Abstract— Role of Response reduction factor in seismic design of EWT is important, thus effect of different foundation system on soil-structure interaction of R.C.C frame staging water tank is carried out for find out effect of soil-flexibility on response reduction factor. For this purpose elevated water tank of storing capacity of 1000 m3 with different filled conditions, different foundation systems (raft, isolated), soil data of different location of Ahmedabad metropolitan city with help of institute of seismological research (ISR). RC water tank is analyzed using displacement controlled non-linear static pushover analysis to evaluate response reduction factor as per ATC-19 with and without considering soil-flexibility. Three different types of soil conditions representatives of hard soil, medium soil and soft soil has been considered in this study. So aim of study is to find out response reduction factors for different soil conditions with different type of foundation systems. Study reveals that isolated footing has higher value of response reduction factor compare to raft foundation. Key words: Raft foundation, Isolated Footing, Elevated Tank, Earthquake Response, Nonlinear Analysis, Soil– Structure Interaction, Response Modification Factor I. INTRODUCTION Indian sub- continent is highly vulnerable to natural disasters like earthquake, draughts, floods, cyclones etc. These natural calamities are causing many casualties and innumerable property loss every year. Water supply is a life line facility that must remain functional following disaster. Most municipalities in India have water supply system which depends on elevated water tanks for storage. Elevated water tank is a large elevated water storage container constructed for the purpose of holding a water supply at a height sufficient to pressurize a water distribution system. These structures have a configuration that is especially vulnerable to horizontal forces like earthquake due to the large total mass concentrated at the top of slender supporting structure. So it is important to check the severity of these forces for particular region. These structures has large mass concentrated at the top of slender supporting structure hence these structure are especially vulnerable to horizontal forces due to earthquakes. All over the world, the elevated water tanks were collapsed or heavily damaged during the earthquakes because of unsuitable design of supporting system or wrong selection of sup-porting system and underestimated demand or overestimated strength. Gareane A. I, S. A. Osman & O.A. Karim discussed the soil and water behavior of elevated concrete water tank under seismic load, and concluded that a significant effect obtained in shear force, overturning moment and axial force at the base of elevated water tank. Dr. Suchita Hirde & Dr. Manoj Hedaoo discussed the seismic performance of elevated water tanks for various Zones of India for various heights and capacity of tanks for different soil conditions. The effect of height of water tank, earthquake Zones and soil condition on earthquake forces are discussed and finally concluded that the seismic forces are increases with Zones and decreases with height of supporting system, seismic forces are higher in soft soil than medium soil, higher in medium soil than hard soil. Earthquake forces for soft soil is about 40-41% greater than that of hard soil for all earthquake Zones. IITK- GSDMA [1] discussed the guidelines for seismic design of liquid storage tanks. Is: 3370 (Part-II) [2] discussed the criteria for earthquake resistant design of structure. IS 1893(Part-I): 2002 [3] discussed the criteria for earthquake resistant design of structure. The value of Response Reduction Factor mentioned in the code of practice IS: 1893:2009(Part-2) [4] “Criteria for Earthquake resistant design of Structures:- Liquid retaining tanks", does not consider the varying soil conditions and effect of foundation system. Considering effect of soil-foundation interaction, response reduction factors will changes due to response of structure different with respect to fixed base conditions. So aim of study is to find out response reduction factors for different soil & foundation conditions. The study presented here is been carried out for the Reinforced Concrete Intze Type Elevated Water Tank of storing capacity of 1000 m3. The effect of the Soil structure interaction of this structure is analyzed using FEM Software SAP2000 [5]. The Soil data that has been used for studying the SSI, has been provided by Institute of Seismological Research (ISR). The variations that have been included for the study are as below: Varying foundation conditions of the ESR i.e. Fixed base, isolated footing and raft foundation. Different water level conditions of the tank i.e. Empty, Half and Full condition. Different types of soil conditions for different locations of Ahmedabad city. II. CONCEPT OF RESPONSE REDUCTION FACTOR Response reduction factor plays important role in seismic design of ESR, which is dependent on three parameters over-strength, redundancy and ductility. The response reduction factor or force modification factor R reflects the capacity of structure to dissipate energy through inelastic behavior. It is a combined effect of over-strength, ductility and redundancy represented as R=Ωo*RR*Rμ. ………….(1) Over strength factor (Ωo) accounts for the yielding of a structure at load higher than the design load due to various partial safety factors, strain hardening, oversized members, confinement of concrete. Non-structural elements also contribute to the over strength. Ductility factor (Rμ) is a ratio of ultimate displacement or code specified permissible displacement to the yield displacement. Higher ductility implies that the structure can withstand stronger shaking
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Effect of Different Foundation Systems on Response ... that isolated footing has higher value of response reduction factor compare to raft foundation. Key words ... 1893:2009(Part-2)
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IJSRD - International Journal for Scientific Research & Development| Vol. 4, Issue 03, 2016 | ISSN (online): 2321-0613
All rights reserved by www.ijsrd.com 867
Effect of Different Foundation Systems on Response Reduction Factor of
R.C.C Frame Type Staging using Non-Linear Static Push-Over Analysis Gajera Jatin H1 Prof. Modi Poonam I2 Pancholi Vasu V3
1P.G. Student 2Assistant Professor 3Senior Geologist 1,2L.D. College of engineering, Ahmedabad 3Institute of Seismological Research, Gandhinagar
Abstract— Role of Response reduction factor in seismic
design of EWT is important, thus effect of different
foundation system on soil-structure interaction of R.C.C
frame staging water tank is carried out for find out effect of
soil-flexibility on response reduction factor. For this purpose
elevated water tank of storing capacity of 1000 m3 with
different filled conditions, different foundation systems (raft,
isolated), soil data of different location of Ahmedabad
metropolitan city with help of institute of seismological