Inestability of thin reinforced concrete u?shaped walls under earthquake loading: transferring knowledge and improving local experimental facilities to better assess and mitigate seismic risk

Mid to high-rise reinforced concrete buildings with thin walls and single layer of reinforcement are a common typology in some south american countries. unfortunately, little is known about the potentially critical development of out-of-plane instability modes of u-shaped members during earthquake loading. the present project addresses this research gap in order to better estimate the seismic risk and enable appropriate remedial measures. an experimental campaign will be carried out by improving the laboratory testing abilities of the colombian partners.

Carry out the first known experimental tests on reinforced concrete (rc) u?shaped thin walls with a single layer of reinforcement, which are commonly used in colombia for the construction of mid and high?rise low cost residential buildings in moderate and high seismic hazard zones. understand the influence of earthquake strike direction on the response of thin u?shaped walls, namely with respect to out?of?plane flange instability. for this purpose, three identical test units will be subjected to diagonal loading along different angles. knowledge transfer from epfl to colombian partners with respect to experimental testing of rc u?shaped walls, including loading control systems and application of innovative instrumentation techniques. validation of advanced and simplified numerical simulation techniques for thin rc u?shaped walls. vulnerability assessment of rc buildings with thin walls of different geometrical shapes.

(i) the collected experimental results and data analyses of a number of test campaigns on specimens with a single layer of reinforcement, namely two rectangular thin rc walls, 15 thin columns under cyclic tension and compression, and the current three u?shaped walls; (ii) their experience on advanced modelling of rc walls making using of finite element software such as opensees, vector4, and diana (which has the capability of simulating the out?of?plane instability response of thin walls); (iii) the development of equivalent fibre?based beam models that represent the behaviour of the edge region of the wall, also accounting for nonlinear material and geometrical effects; and (iv) new simplified mechanical models to predict the out?of?plane response of rc walls based on the member geometrical and mechanical characteristics. the previous points are the outcome of the ongoing collaboration between the eesd lab and the colombian partners since 2013. the most important findings will also be presented at two conferences aimed at different target audiences. the 16th world conference on earthquake engineering (16wcee), which will be held in santiago, chile, between the 9th to the 13th of january 2017, will attract worldwide researchers and engineers.