Determination of the earthquake safety of a special structure and strengthening with steel members

Our country is located at one of the most effective eartquake line in the world. Because of that, greate loss of life and property was occured after greate earthquakes. These damages are seriously effected people, economy, life standarts and residential. Therefore, new buildings need to ensure earthquake strength, after earthquakes occured at last decades. Also, existing buildings are required determination of earthquake damages, refitment and strengthening. The purpose of refitment is bring back the previous situation. On the other hand, strengthening is purposed to surpass the previous situation. design of earthquake-resistant buildings and behaviour of existing buildings are investigated deeply with increasing informations and improvments about earthquake engineering and the development of computer technology. In this way, performance-based building design has gained importance. Performance-based building design application is more hard than old design method force-based design. When design a building, the strength and durability against external effects of building is examined. Based on force design is applied using external forces. In this way, internal forces calculated with effected external loads. Based on performance design is applied with earthquake effects. Earthquake behaviour is not certain so earthquake effects can not be estimated. The reason of this, we don't know certainly when or where earthquake will occur, we just estimate that. Because of that, calculation of performance-based building design is difficult to determine the earthquake behaviour of a structure. Increasing knowledge and improvments about earthquake engineering needs a document to be appliable. Firstly, performance-based building design concept was mentioned at 2007 seismic code.2007 seismic code suggests linear and nonlinear analysis for performance-based building design. The aim of the nonlinear method is determined, evaluated and compared with limit values capacity of stress and strain. Linear and non-linear methods are developed at performance analysis. Earthquake Code use for determination of the earthquake safety of existing buildings and strengtening in our country. Computer programs are used common for application of this code. This computer programs can analyze linear and non-linear methods. Nonlinear analysis methods are incremental equivalent earthquake load method, incremental mode superposition method and time history method. Using computer program, essential controls are made in the buildings for performance targets. For essential controls, linear and non-linear methods are used for analysis to buildings. In this thesis, incremental equivalent earthquake load method is used for determination of hinge type at model. Time history method is used to evaluate current situation and reinforcement model. Performance levels and building performance targets are examined according to results and comparisons. There are seven parts in this thesis. These parts are introduction, determination of earthquake safety in existing system, non-linear analysis, reason of strengthening, strengthening of Structural and Earthquake Engineering Laboratory with steel braces, results and general results and suggestion are obtained from this thesis. In this work, Istanbul Technical Univercity Ayazağa Campus, Civil Faculty L1 Block, which is one of the L1-L2-L3-L4 Blocks and involves Istanbul Technical Univercity Structural and Earthquake Engineering Laboratory was examined for eartquake safety of building. Also, It was determined why this building needs to strengthening, investigated what can be done for strengthening of building and compared. Lastly, suggestions were presented with available datas from in this study. The building was built in 1976 and has a calculation reports and reinforced drawings. Mathematical model of structure was created using SAP2000 program with available datas and some accepted assumptions. loads are assigned to SAP2000 model of current building. Linear and non-linear methods are analyzed for determine eartquake safety of structure, after mathematical model was created. Then equivalent earthquake load calculation is made according to 1975 and 2007 seismic codes and compared results for current situation. Mode superposition method is used to control of relative storey drifts, shear safety of colums and shear walls in existing model. Preliminary study was applied before non-linear analysis applied to SAP2000 model of current building. Preliminary study is involves two dimensions frame system and three dimensions frame system model. Linear and non-linear analyzes are made for that models. Incremental equivalent earthquake load method applied to example models to determine which hinge types applied to current model. After that, non-linear analyzes are made for mathemetical model of current structure. Active bending rigidities and nonlinear material models are determined for nonlinear analyzes. Non-linear time history method applied to determine the damage limits of existing model. Reasons of strengthening are examined according to calculations and obsevations. After that, strengthening model is determined and evaluated. Performance levels and building performance targets are explained. As a result of the analyzes made, the current situation of the building was determined by collaboration. Then, two separate reinforcement models were created and examined after current situation of buulding was determined. Two reinforcement model was suggested for strenghtening of structure. One of that models is strengthening with steel members. Building was strengthening with two opposite U reinforced walls at 1997. That walls not extends to roof, they are cut in first floor. Because of that, irregularity was occured. Strengthening with steel braces from top of the U reinforced walls to roof will solve irregularity problem and stifnees of building will increase. The other model is suggested lift heavy roof floor and place steel truss roof system. Suggestions are presented to choose the most effective strengthening model. Cost analysis was made for helpful to choose. Strengthening of structure with steel brace was examined. Profile of steel members are determine according to seismic and vertical loads from mode superposition method analysis. In strengthening model, steel walls are above the U shear walls. Steel walls are surrounded with H profiles and included tube brace members. Steel walls are applied interior of building. Truss system was created with tube braces for outside of building at roof floor. Connection of steel members to reinforced concrete and each other design on Tekla Structure and IdeCAD programs. After reinforcement, the situation of building was inspected and interpreted. Cost and quantities calculations are made for strenghening model. Finally, current structure and enforced structure was compared according to results of mode superposition method and non-linear time history.Results are compared according to general base, storey base and element base. Top displacements and seismic base reactions are compared at general base. Storey displacements and relative storey drifts are compared at storey base. Strains, moment-curvature relation ship, moment-axial load relationship of colums are compare in element base. Finally, the enforced structure was reached to desired performance level.