STRENGTHENING OF EXISTING REINFORCED CONCRETEBUILDINGS AND NEAR FAULT EFFECTS

摘要

The seismic evaluation and the retrofit design of an existing reinforced concrete building due to seismicloads is a very important problem of most of the earthquake prone countries. In this paper performance ofan existing seven story RC building is analyzed according to the 1998 Earthquake Code of Turkey andfound to be weak and strengthened by jacketing certain columns and by adding shear walls to thestructure. Since there are no set rules for strengthening procedure in this code, the same criterion has beenused for the design of new buildings utilizing the design earthquake spectrum given in the code. Thisresult has been tested using ATC – 40 guidelines and the capacity spectrum method by idealizing thestructure as two and three dimensional models. The results show that 2D model is as good as 3D model.Capacity spectrum method also shows that the building needs to be strengthened. The Earthquake Code ofTurkey does not require any specifications for near fault earthquakes. In order to see the effect of nearfault earthquakes, a nonlinear time history analysis has been carried out using five ground motions ofrecent earthquakes. The results show that the maximum story drifts are exceeded the code values at everystory due to Bolu record of 1999 Duzce Earthquake and also the largest base shear occurs for this record.The story drifts are also exceeded for the second, third and fourth stories for Duzce record of 1999 DuzceEarthquake and 1992 Erzincan Earthquake. There are also some plastic hinging developing in the newlyadded shear walls at the first, second and third stories. As a conclusion, the near field fault effects have tobe introduced to the Turkish Earthquake Code for the new and the strengthened buildings. This isespecially important along the North Anatolian and East Anatolian Faults.