EFFECT OF INFILLS ON THE GLOBAL BEHAVIOR OF R C FRAMES - ENERGY CONSIDERATIONS FROM PSEUDODYNAMIC TESTS/

A series of pseudo-dynamic tests were conducted on a full-scale four-s torey reinforced concrete building designed according to Eurocodes 2 a nd 8. The building was 10 m long, 10 m wide, and 12.5 m high. It was d esigned as a ductility class 'High' structure, for typical live loads and for a peak ground acceleration of 0.3 g and medium soil conditions . A first test was conducted on the bare frame. The project was carrie d out within the framework of the European Association of Structural M echanics Laboratories (EASML), and was designed to assess the adequacy of the damage indicators to be used in the calibration of Eurocode 8. The pseudodynamic test was conducted by using an artificially generat ed earth-quake derived from a real earthquake (Friuli, 1976), with nom inal acceleration 50 per cent larger than the value adopted in design. The structure performed as expected. The pattern of the measured rota tions was that of a weak-beam, strong-column mechanism. The fundamenta l frequency of the structure after the test was found to be half of th e initial value, but the damage was limited and uniformly distributed. A second experimental programme was conducted as part of the work of the Network Prenormative Research in support of Eurocode 8, to study t he influence of masonry infill panels on the global behaviour of the f rame. Two pseudodynamic tests were conducted, with different infill pa tterns. A test was performed by infilling the two external frames with hollow brick masonry in all four storeys (uniform infill distribution ). The test was then repeated on the structure without infills at the first storey, to create a soft-storey effect. The input signal was the same as in the tests on the bare frame. The purpose of the tests was to study the effects of the different layouts of infills, as well as t o calibrate the computer models for the infills to be used in parametr ic analyses. In this paper the test results are presented and the perf ormances of the structure with different infill configurations are com pared. The global behaviour of the structure is compared with the pred ictions which could have been made with simplified approaches. In part icular, single degree of freedom energy concepts are used to verify if the differences in the global behaviour could have been predicted. Th e differences in the single degree of freedom energy demands with resp ect to the bare frame may be used as a means of accounting for the pre sence of irregular distributions of non-structural infills in the simp lified design of the frame.