@article {693, title = {Hybrid Simulation of Bridge Pier Uplifting}, journal = {Bulletin of Earthquake Engineering}, year = {2015}, abstract = {

Substructured Pseudodynamic (PsD) testing is used to study the transverse seismic response of a bridge with box-girder deck monolithically connected
to circular piers, but free to move laterally at the abutments. The tests are of two types, each one with two variants: with the pier footing rocking on elastic soil and
uplifting from it, or fixed to rigid ground. The first type concerns a two-span deck connected monolithically to a central pier and supported at each end on the abutment
through a pair of elastomeric bearings, which are stiff and strong in compression but very soft and weak in tension. The second one concerns the interior
piers of multi-span bridges having all spans equal and all piers similar. The pier was physically tested at 1:2 scale; everything else was numerically simulated
online with Opensees. The deck, the soil and the bearings were modeled as elastic, but not allowing tension to develop at the soil-footing interface, and the bearings
two orders of magnitude more flexible in tension than in compression. In the first type of tests, at a peak ground acceleration (PGA) of 0.15g, the footing uplifted,
the bearings developed tension, but the pier stayed elastic. In the second type of tests, with a PGA of 0.4g, uplifting of the footing did not prevent plastic hinging at
the pier base, but reduced significantly the pier damage. A cyclic quasi-static test in the end shows the deformation capacity margins of the pier.

}, keywords = {bridge piers, distributed testing, Foundation uplifting, Hybrid simulation}, author = {Stathas, N and Skafida, S and Bousias, SN and Fardis, MN and Digenis, S and Palios, X} } @conference {691, title = {Properties of RC walls produced by infilling a frame with concrete for seismic rehabilitation}, booktitle = {SMAR-2015 3rd Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures }, year = {2015}, address = {Antalya, Turkey}, abstract = {

In seismic retrofitting of concrete buildings, frame bays are converted to reinforced concrete (RC) walls by infilling the space between the frame members with RC of a thickness of not more than their width. The cyclic behavior of the resulting wall depends on the connection between the RC infill and the surrounding RC members. The paper uses results from 48 cyclic tests of such composite walls to express their properties in terms of the geometry, the reinforcement and the connection. Properties addressed are: a) the yield moment at the story base; b) the secant-to-yield-point stiffness over the shear span of the wall in a story; c) the deflection at flexural failure in cyclic loading; d) the cyclic shear resistance, including sliding shear. Separate models are given for squat walls failing in shear. The models are modifications of the ones developed in the past for monolithic RC walls from several hundred cyclic tests.

}, author = {Biskinis, D and Psaros-Andriopoulos, A and Fardis, MN} }