International Conference on Civil Engineering Architecture & Urban Sustainable Development 27&28 November 2013, Tabriz, Iran A Comprehensive Study on the Seismic Behavior of Double-Layer Space Structure Domes Abbas Habibi, Hossein Rahnema, Abdolhossein Baghlani, Behtash JavidSharifi 1. M.Sc. of Earthquake Engineering, Shiraz University of Technology (abas.habibi82@yahoo.com) 2. Assistant professor of the Civil and Environment Engineering Department, Shiraz University of Technology (rahnema@sutech.ac.ir ) 3. Assistant professor of the Civil and Environment Engineering Department, Shiraz University of Technology (baghlani@sutech.ac.ir) 4. M.Sc. student of Earthquake Engineering, Shiraz University of Technology (b.javidsharifi@sutech.ac.ir) Abstract In this paper the seismic behavior of double-layer dome space frames supported by the ground has been inspected. The considered models are of diameters between 20 and 80 meters, varying in the length and height of the dome. The ratio of height to span diameter of the domes is taken constant and equal to 0.2. Designing has been carried out based on AISC-LRFD93, and assuming an initial seismic behavior factor. In order to assess ductility coefficients, over- strength factors and the seismic behavior of the inspected structures, an iterative trial-and-error process is made. Using the program specifically written for this inspection, the bilinear curve correspondent to the push-over curve for each model is drawn with the proper tolerance. Using this program, ductility coefficients, over-strength factors and seismic behavior factors are calculated according to common ductility reduction factor equations. Results of this research show that in double-layer dome space frames, ductility, over-strength and seismic behavior factors reduce with the increase of span diameter. Key words: Seismic behavior factor, Ductility coefficient, Seismic behavior, Push-over analysis, Dome space frames 1. Introduction With the growth of different computer software programs and their capability of designing huge structures with large numbers of elements and degrees of indeterminacy, the use of space frames is growing day after day. Among different types of space frames, double-layer domes may be more made use of by structural engineers and architects as a result of their high lateral and vertical stiffness, the capability to fill big spans with no need of internal columns and their architectural attractiveness. The dead load caused by the weight of the structure, the load of snow, wind and earthquake are taken into account to design these structures. The dead load and the loads of wind and snow are easy to calculate with a good tolerance regarding the expected application and the region of establishment based on manuals existing in loading codes and the Space Frames Code. Yet, the assessment of lateral loads caused by earthquake for linear analyses meets some unreliability because of the absence of definite behavior factors. Therefore, it seems that the inspection of seismic behavior and behavior factor assessment of these structures is necessary.