Global and local demand limits of thin reinforced concrete structural wall building systems

Industrialized construction system used in some Latin American countries are build based on elements which are of special interest because the geometry of their cross section, and layout of longitudinal reinforcement may facilitate the triggering of flexural-compression failures. This is so because of the excessive compressive demand on a thin-poorly-detailed web that arises due to seismic action. Given the large unsupported length of the web close to the critical section at the base, the extreme portions of these elements are also prone to lateral (out-of-plane) instability when subjected to cycling loading. This paper presents and analyzes a database of reinforced concrete thin-wall buildings representative of building archetypes in some countries in the southern hemisphere of the Americas. Variables of interest such as wall area index, fundamental period, flanged-wall cross section geometry, wall aspect ratio, reinforcing steel detailing, axial load ratio, building period, neutral axis depth, shear span ratio, among others, are analyzed in detailed. A drift coupling factor is introduced to evaluate the impact of coupling of the surrounding system on individual walls. An archetype wall representative of the buildings in the database is selected by means of a multivariate statistical analysis. This prototype will serve as subject of laboratory testing. The paper also presents and discusses the results of a reversed-cyclic-loading experiments on a rectangular and T shape reinforced concrete thin-wall with aspect ratio of 3 and 3.7. The specimens are representative of the construction practice in intermediate seismic hazard areas in Colombia. Results suggest that this type of elements have limited ductility capacity, inferior to the expected behavior promoted by the building codes. Global and local deformation parameters from experimental data are discussed.