Shaking table test design to evaluate earthquake capacity of a 3-storey building specimen composed of cast-in-situ concrete walls

This paper presents the works developed to design a test at the EUCENTRE Laboratory in Pavia, within a SERIES project, for the evaluation of the maximum capacity of a 3-storey building under an earthquake. The structural system of this building is composed of cast in-situ sandwich squat reinforced concrete walls which make use of polystyrene as a support for the concrete. This structural typology is widely used for construction in non seismic areas or in areas of low seismicity, and appreciated for their limited building costs, limited installation times, great constructions flexibility and high energy and acoustic efficiency. In recent years, an exhaustive experimental campaign, carried out by the University of Bologna and the EUCENTRE in Pavia, was devoted to the assessment of the performances of single walls and of a portion of structure through cyclic tests under horizontal loads. However their seismic behavior has not been fully investigated. The purpose of this test is to verify the dynamic behavior of this structural typology under earthquake loads. Previous to the tests, an extensive analytical and numerical research has been developed to predict some results on some models of the building. The structural specimen which will be tested is a full-scale 3-storey structural system composed of cast-in-situ squat sandwich concrete walls characterized by 5.50 x 4.10 m in plan and 8.25 m in height. Shaking table tests are currently under design and development to validate the theoretically and partially-experimentally anticipated good seismic behavior of cellular structures composed of cast-in-situ squat sandwich concrete walls. The input for the simulation will be the Montenegro earthquake, which measured 7.0 on the Richter in April of 1979. The tests will be performed in Dec. 2011 and the first results will be soon determined. The construction of this building was developed out of the main laboratory; it was lifted and pulled inside using hydraulic jacks and a roller system that reduces the friction coefficient on the ground surface less than 0.1. This process produces several changes on the final boundary conditions; in fact a prestress system has been designed for the building and the foundation to assure the integrity of the structure during all the process. The selected laboratory has a shaking table that consists of a single degree-of-freedom (uniaxial) rigid platform of 5.6mx7.0 m, with a payload range between 70 to 140 t and a peak acceleration with a maximum payload 1.8g. The maximum force is 2100 kN and the maximum overturning moment capacity is equal to 4000 kNm. For the data acquisition system this laboratory includes a 250-channel system based on 18 bit hardware and an advanced wireless system based on 8 high definition digital cameras. The geometry of this shaking table and the capabilities of this facility are suitable to make the proposed test. The previous analysis developed will guarantee the correct behavior of this building during the seismic test.