1st Croatian Conference on Earthquake Engineering 1CroCEE 2021

Due to the rapid expansion of urban areas around the world and the ever-increasing number of reinforced concrete (RC) structures serving a variety of functional purposes, their behaviour in case of major seismic events has become of great interest to researchers and decision makers alike. Although initially designed to ensure certain levels of safety in case of earthquakes, the damage accumulated in a reinforced concrete structure during its lifetime due to seismic events will ultimately require its strengthening in order to comply with the new seismic design regulations.
The paper presents the results obtained by numerical analyses of the seismic performance of a scaled-down RC frame structure retrofitted with a composite membrane. The 1/3-scale symmetric structure was designed according to the specifications of the European norms and following the guidelines in the national annex for Romania. The RC frame structure was previously damaged during a series of shake table tests. The numerical model was developed based on the initial undamaged state of the frame structure and was validated by comparing the numerical results to the experimentally obtained results.
A non-linear time history analysis (THA) was used in order to account for the damage accumulation in the model from one seismic record to the next. Modal analysis was run after each non-linear THA to determine any change in the fundamental period of vibration. The seismic record consisted in an artificial earthquake generated according to Eurocode 8 using soil type C spectrum, the amplitude of which was gradually increased from one loading scenario to the next.
The numerical model was then updated to include the effect of strengthening by means of composite membrane. The obtained results were used to estimate the outcomes of a new series of shake table tests on the strengthened model following the same loading set-up in terms of seismic motions.