Seismic analysis evaluation of an existing steel structure in accordance with Turkish and European standarts using also time history method and real acceloragrams

Ground fault movements, namely earthquakes are one of the most destructive disaters in terms of causing deaths and major economic losses. This is the main reason why seismic analysis results control the major part of structural designs in especially our country which is located in an active earthquake zone. In order to design earthquake resistant structures, various different regulations and codes are arranged all over the world for the aim of determining the quake forces acting on the structure. According to Turkish Seismic Code 2007, the linear and nonlinear techniques which the codes mentioned above consist of could be classified under three titles. The first of these is the Equivalent Static Seismic Forces method which is based on transforming the dynamic ground motions to their static corresponding forces, while the second one is named Response Spectrum Analysis Method which mainly requires the superposition of the modal shapes and the third technique is Time History Analysis-whose base is the real time earthquake records or simulated ones. CEN (The European Comittee For Standardization) a commition putting together the national design codes of thirty three European countries, is the creator of Eurocode series. In order to take the specific conditions which these countries posses into account, National Annexes are created for every each member country. The series basicly includes nine parts. These parts are numbered 0 to 9 and respectively describe basis of structural design, actions on structures, concrete design, steel structures design, composite structures design, timber structures design, masonry structures design, geotechnical design, sesimic design of structures and design of aluminium structures. In the scope of this investigation Eurocode 0, Eurocode 3 and Eurocode 8 have been studied. Eurocode 0 describe the fundamentals of structural design while Eurocode 3 specifically states the design principles of steel structures. Eurocode 8 is a procedure about the design of structures for earthquake resistance describes the ground motion of a point via defining an elastic response spectrum. Time history analysis supplies the chance of determining more exact sesimic design forces. The parameters and features of the quake chosen shall be compatible with the ground where the structure analyzed is loacated. There are requirements for the strong ground motion accelerograms to be used in accordance wtih Turkish and European codes in terms of duration of the records, minimum ratios of the spectrums of the records with respect to the target spectrum and which time interval these target ratios will be searched. Although the requirements mentioned above are similar to each other in the codes, the difference of the elastic spectrums lead the designer to use different scale factors in order to make them compatible with the target spectrums. In this study, a seismic analysis comparison is done and an existing steel structure. This is a steel framed four story parking building which is located in Bayrampaşa, İstanbul, having a rectangular shape on the plan view. Different from the real structure, two axes intervals that include steel ramps are not taken into account while creating the analysis model, so that an opportunity of observing the structural system of the steel structure behaviour alone. The contour dimensions of the building taken into account fort he study are mainly: 47,40 meters on the long and 30,00 meters on the short directions. The structure resists the lateral forces through concentric bracings along its long direction and concentric braced moment frames along its short direction. The behaviour factors for the same lateral force resisting systems are assesed different in Turkish and European sesimic design codes. SAP2000 v.16.0.0 is chosen as the analysis and design programme. The dead and live loads are taken from the original project competible with the use of the structure while the wind loads are handled from Eurocode 1-4. Since the building has no cover on its facades, the wind load is only taken into account on the roof. The snow loads are also applied according to Eurocode 1-3. Afterwards, these loadings have been acted on the structure.The seismic analysis method is LinearTime History Anaysis. In that case, real accelorograms-considering their actual seismological parameters-are scaled in order to make these ground motions compatable wtih the elastic design spectrum of Turkish Design Code 2007. Three different acceleration records for an earthquake which is essential for engineering history is chosen. This strong ground motion belongs to El Centro Earthquake (1940, Imperial Valley, Southern California, The United Stetes of America). There are three accelerograms recorded at different locations which are supplied from PEER (Pasific Earthquake Engineering Research Center) and scaled with a coefficient, then turned into the input data for the structural model after verifying that the avarage of these are compatible with the elastic spectrum described in Turkish Earthquake Design Code. The database mentioned is a seismic research and education center which is mainly based on California University, Berkeley. In addition to that the loading combinations also rely on Turkish codes. The first structural analysis model is created as described above. In the scope of second analysis model dead loads, live loads, snow loads and wind loads are all kept the same with the first structural model. The sesismic analysis method is again Linear Time History Analysis which is repeated for Eurocode 8 by scaling the real acceloragrams mentioned above in order to make them compatable with the elastic acceleration spectrum of European code. Since the surface wave magnitude of the eathquake chosen is greater than 5,50 the target spectrum is type 1 elastik response spectrum. The combinations of actions are also written according to Eurocode 0 and Eurocode 3. In conclusion, the seismic analysis technique is the same while the elastic spectrums aimed are different in these two sapatial models mentioned. The analysis results are compared by observing the behaviours of the structure in two models. The behaviour term here states detecting the natural frequences, rigidities, lateral displacements, base shears and story shear forces. In conclusion, the results are demonstrated with both graphics comparing the base shear forces and lateral displacements of two model and their tabulated form in addition to these the story shears are listed for every earthquake loading. Moreover the equivalent static sesimic forces for two models are calculated and compared with time history methods' result base shears. To conclude with, the design results to Turkish and European design codes are assesed. The states of capactiy ratios and conditions required at sesimic joints are evaluated.