PRESENTATION ON 3D SHAKE TABLE

PRESENTATION ON 3D SHAKE TABLE

Prepared by:- PRATEEK KAR It is a pure reinforced concrete 3d frame with infill walls specified in such a way to take into account some of the common irregularities & deficiencies in these types of buildings during past earthquakes.In order to reproduce actual earthquake data, a 6 degree of freedom shaking table is essential.It is a very complex electro hydraulic system which is very expensive & requires high maintenance & operational costs. About 3d shake table:-Severe damage resulted from the last major earthquakes in Turkey strongly emphasized the need of proper repair & strengthening of concrete buildings in order to avoid catastrophic losses & have safer & stronger buildings.

History &origin:-The 1st planning meeting was held in April 2004 in shin-kobe,japan with the participation of nearly 50 researchers from Japan &US. the 2nd & 3rd planning meetings were held in Arlington,USA in July 2004 & Miki,Japan respectively.Initial conferences on curbing sesmic activities:- Three 1/3rd scale (2 storey RC frame specimens) of a 4 storey RC frame building prototype have been designed,constructed & tested on the shaking table at IZIIS lab. Initial specimens of shake table:-Additional carbon fiber reinforced polymer(CFRP) strips were placed on the inner & outer faces of the masonary infill constructed in the middle bay of boyh stories.The existing infill wall was reinforced with a very thin layer of high strength pre-cast concrete elements epoxy glued to the wall & to the frame members.Construction:-

3d shake table layouts

Mainly it was built to advance the scientific knowledge in earthquake engineering as a consequence of the extensive damage of urban infrastructures.Research includes progressive failure ,soil foundation structural interaction ,liquefaction-induced lateral displacement & forces ,retrofit strategies & measures ,protective systems & responses to spatially varying ground motions & failure of RC columns.Construction:-

Shake tables prepared by L.D. College of engineering are uni-axial electro-mechanical shaking tables. These shaking tables are assembly of various steel sections that forms a table on which a plate is supported.Movement of this plate is considered shaking of ground due to earthquakes. Uniaxial means movement in one horizontal direction.Implementation of shake tables in laboratory:-Uni-axial motorized electro-mechanical shake table.Size: 8ft X 4ft table platform for fixing modelOperated manually & with motor as well.Motor: single phase DC motor with electronic panel board,frequency range of 0-1500 rpmAmplitude range of shake table is from 0-100mmHarmonic & periodic simulationFrequency of simulation: 0-4HzPayload capacity:-600kg

Specifications of low frequency shake table:-Uni-axial motorized electro mechanical shake table.Size:-5ft X 3ft table platform for fixing modelOperated manually & with motor as wellMotor:-single phase DC motor with frequency range of 0-9000rpmAmplitude range:-0-50mmHarmonic &random simulation.Frequency of simulation:-0-25 HzPayload capacity:-500kg Specifications of high frequency shake table:-

3d shake tables

Infill wall RC strengthening panels.Panels are made of concrete having strength of 40 Mpa &reinforced with steel plain bars.SIKADUR 31 epoxy repair mortar was used in panel joints & between the panels & the wall plaster.It is a 2 component mortar with setting time of about 45 minutes at room temperature & the tensile strength of about 20 Mpa.Steps of incorporation:-To clarify the failure mechanisms of RC columnsTo clarify the effectiveness of standard seismic retrofit measures for existing RC columnsTo clarify the effect of damper technology

Objectives of 3D shake table:-First a shear-slip failure between the concrete elements & masonary infill wall due to poor connection has been observed.Then a brittle shear-slip failure between the columns & foundation due to inadequate stirrup lap-splice-length occured. those deficiencies have been overcome using proper retrofitting techniques with CFRP strips ,particularly applied on affected lap splice zones between the columns & foundation.Failures:-The random earthquake ground motions, which cause the structure to vibrate ,can be resolved in any 3 mutually perpendicular directions(+x , +y , +z,-x,-y,-z). i.e 2 horizontal & 1 vertical. Horizontal movements are pre dominant.The vertical direction movements are to 2/3 rd of the horizontal vibration. self weight of the load compensates the effect of vertical acceleration. Movement of shaking table means application of strong accelerographs to model of the structure to study the behaviour.Physical significance of shake table:- The proposed retrofitting techniques have significantly reduced the displacements ( dmax dropped from 16.8cm to 8.7 cm & then to 2.26 cm for the retrofitted specimens) & improve the structural behaviour. Newer & better innovations are yet to come in this field.

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