SEISMIC VULNERABILITY ASSESSMENT OF IRREGULAR … · shapes of first and second modes ñ ë 61 å A...
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SEISMIC VULNERABILITY ASSESSMENT OF IRREGULAR REINFORCED CONCRETE BUILDINGS IN AUSTRALIA © BUSHFIRE AND NATURAL HAZARDS CRC 2017 Alireza Mehdipanah 1,2 , Elisa Lumantarna 1,2 , Nelson Lam 1,2 1 Department of Infrastructure Engineering, The University of Melbourne, Parkville 3010, VIC 2 Bushfire and Natural Hazards Cooperative Research Centre, Melbourne Australia SEISMIC DESIGN AND ASSESSMENT OF IRREGULAR REINFORCED CONCRETE BUILDINGS IN THE REGIONS OF LOW TO MODERATE SEISMICITY SUCH AS AUSTRALIA IS INVESTIGATED THIS POSTER. 1. INTRODUCTION Reinforced concrete buildings constitute a significant proportion of constructions in Australia. Many existing buildings in Australia and other low to moderate seismic regions have been designed with little to no consideration of ductile detailing. The majority of these buildings also possess irregularities which can exacerbate their vulnerability in an earthquake. 2. STUDIES BASED ON LINEAR RESPONSE Seismic response of 75 buildings with various locations and extent of irregularities in elevation was evaluated. 2.1 Irregular buildings behaviour Comparison between the seismic response of vertical regular and vertical irregular buildings have shown that discontinuities in columns within the building do not result in soft-storey mechanism. 2.2 Generalised lateral force method (GLFM) of analysis Seismic design codes of practice require the use of dynamic analyses for irregular buildings. However, dynamic analyses can be computationally expensive and require expert judgment, especially as far as three-dimensionally modelling is involved. A building to be assessed Periods of the modes of vibration of buildings 2.3 GLFM for torsionally balanced (TB) buildings Using the suggested generalised mode shapes, a simple method were developed to estimate the displacement profile of taller buildings. 2.3 GLFM for torsionally Unbalanced (TU) buildings The simplified method has been extended to account for the effects of torsion due to plan asymmetry. ߜ ൌ ∑ ߜ ଶ ∑ ߜ ൌ ∑ ߜ ଶ ∑ ߜ ଶ a ൌ Comparison of the displacement profiles based on the proposed GLFM and dynamic method Comparison of the displacement profiles based on the proposed and dynamic method Generic mode shapes of first and second modes ௫ ଶ 1 ଶ ଶ ݔ ߠെ Ω ଶ 1 0 0 1 ݔ ߠൌ 0 0 3. STUDIES BASED ON NONLINEAR RESPONSE Ductility and failure behaviour of multi-storey buildings featuring discontinuities is investigated. 3.1. Component modelling A systematic analytical modelling technique for the simulation of limited-ductile beam-column elements is proposed. 3.2. Building modelling Using the proposed technique, OpenSEES finite element package employed to build 3D case study models. 3.3. Observed mechanisms Shear failure in the transfer beam occurs prior to the point that structure reaches the calculated target displacement for some cases.
Transcript of SEISMIC VULNERABILITY ASSESSMENT OF IRREGULAR … · shapes of first and second modes ñ ë 61 å A...
SEISMIC VULNERABILITY ASSESSMENT OF IRREGULAR
REINFORCED CONCRETE BUILDINGS IN AUSTRALIA
© BUSHFIRE AND NATURAL HAZARDS CRC 2017
Alireza Mehdipanah1,2, Elisa Lumantarna1,2, Nelson Lam1,21 Department of Infrastructure Engineering, The University of Melbourne, Parkville 3010, VIC2 Bushfire and Natural Hazards Cooperative Research Centre, Melbourne Australia
SEISMIC DESIGN AND ASSESSMENT OF IRREGULAR REINFORCED CONCRETE BUILDINGS IN THEREGIONS OF LOW TO MODERATE SEISMICITY SUCH AS AUSTRALIA IS INVESTIGATED THISPOSTER.1. INTRODUCTION
Reinforced concrete buildings constitutea significant proportion of constructionsin Australia. Many existing buildings inAustralia and other low to moderateseismic regions have been designed withlittle to no consideration of ductiledetailing. The majority of these buildingsalso possess irregularities which canexacerbate their vulnerability in anearthquake.
2. STUDIES BASED ON LINEAR RESPONSE
Seismic response of 75 buildings withvarious locations and extent ofirregularities in elevation was evaluated.
2.1 Irregular buildings behaviour
Comparison between the seismicresponse of vertical regular and verticalirregular buildings have shown thatdiscontinuities in columns within thebuilding do not result in soft-storeymechanism.
2.2 Generalised lateral force method(GLFM) of analysis
Seismic design codes of practice requirethe use of dynamic analyses for irregularbuildings. However, dynamic analysescan be computationally expensive andrequire expert judgment, especially asfar as three-dimensionally modelling isinvolved.
A building to be assessed
Periods of the modes of vibration of buildings
2.3 GLFM for torsionally balanced (TB)buildings
Using the suggested generalised modeshapes, a simple method weredeveloped to estimate thedisplacement profile of taller buildings.
2.3 GLFM for torsionally Unbalanced (TU)buildings
The simplified method has been extendedto account for the effects of torsion dueto plan asymmetry.
∑∑∑∑
a
Comparison of the displacement profiles
based on the proposed GLFM and
dynamic method
Comparison of the displacement
profiles based on the proposed and dynamic method
Generic mode
shapes of first and second modes
1Ω 1 0
0 100
3. STUDIES BASED ON NONLINEARRESPONSE
Ductility and failure behaviour ofmulti-storey buildings featuringdiscontinuities is investigated.
3.1. Component modelling
A systematic analytical modellingtechnique for the simulation oflimited-ductile beam-columnelements is proposed.
3.2. Building modelling
Using the proposed technique,OpenSEES finite element packageemployed to build 3D case studymodels.
3.3. Observed mechanisms
Shear failure in the transfer beamoccurs prior to the point that structurereaches the calculated targetdisplacement for some cases.
