Seismic performance of concrete framed buildings with soft and weak story in low to moderate seismic regions | |
| Author | Shrestha, Noorma |
| Call Number | AIT Thesis no.ST-06-13 |
| Subject(s) | Reinforced concrete construction Buildings, Reinforced concrete |
| Note | A thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ST-06-13 |
| Abstract | The structural configuration plays an important role on the seismic behaviour of structures. In the recent earthquakes, irregular structures have shown an inadequate behaviour when compared with similar regular structures. There are several problems in existed buildings and facilities in the region of low to moderate seismicity. Earthquake design codes require different methods of analysis for regular and irregular structures, but it is only recently that the design codes have included specific criteria that define irregular structures. In this study the stiffness and strength limits for regular buildings as specified by the Uniform Building Code (UBC) are evaluated. The main objective of the research is to compare the seismic performance of the irregular structure with soft and/or weak first story structure. The seismic demands investigated are story shears and story drifts. In the analysis, one typical existing RC beam-column frame building is selected and used as the base structure. From regular six irregular frames are defined with three types of irregularities- stiffness, strength and combined stiffness and strength in the first bottom story. The seismic response of irregular structures is assessed by means of elastic and inelastic analysis. Development of modelling techniques of these features is carried out fundamentally based on the recommendations in ATC-40 and FEMA-273/274. The analysis method is nonlinear static pushover and non linear dynamic analysis. The obtained results from the nonlinear pushover analysis are presented in the form of normalized base shear - roof displacement relationship. And the results obtained from nonlinear dynamic analysis are presented in form of story shear demands and story drift demands. The investigation of results shows that the seismic response of the building is more sensitive to strength change rather than stiffness change of similar magnitudes. The presence of soft and/or weak story increases the story drift demands in that story and neighbouring stories and decreases the drift demands in the other stories. The roof displacement is insensitive to the soft and weak first story The results of this study emphasize the importance of performing nonlinear analyses in the evaluation stage for designing new buildings or retrofitting existing ones. Without performing nonlinear analysis it would not be possible to identify the existence of strength irregularities in the structure, which are the most critical types of irregularity affecting seismic demands |
| Year | 2006 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ST-06-13 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Pennung Warnitchai; |
| Examination Committee(s) | Pichai Nimityongskul;Kato, Yoshitaka ; |
| Scholarship Donor(s) | Government of Austria; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2006 |