Evaluation of the soft-storey performance of 2d reinforced concrete frame using natural frequency | |
| Author | Shrestha, Sneha |
| Call Number | AIT Thesis no.ST-22-05 |
| Subject(s) | Reinforced concrete Earthquake resistant design |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Structural Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | Soft Storey structure is a multi-purpose structure normally has wide opening at door, windows, large open spacing in ground floors for Parking, garages, and for some commercial purposes. These types of structure are significantly more flexible in lateral load resistances than the stories above or below it. According to modern, International Building Codes (IBC), floors having 80% less stiffness than the averages stiffness of the stories above or below the open storey are known as soft storey structures. They are commonly practices in Low to moderate seismicity regions such as Nepal, Thailand, India, Myanmar, etc. In recent years, urban and semiurban areas of Nepal have been rapidly growing. Reinforced concrete (RC) with masonry infill buildings has become very popular in these areas. The data obtained showed 90% of building in Nepal practices open storey at ground floor for commercial shutter/ parking and close the upper floor with infill masonry for residential purpose. Nepal lies in the middle of Himalaya region, which is seismically very active. In 2015 Gorkha earthquake, most of these practices open storey were collapsed. Various techniques are implied to improve these buildings like steel jacketing, carbon fiber wrapping, base isolation is not economically feasible, and solutions suggested by many building codes, to design the ground for higher base shear, does not give the satisfactory performance. The consequences: people are continuing to construct similar buildings or using the same vulnerable buildings and this trend seems to continue. As these building’s performances are improving according to other types of building so the given solution is not showing effective solutions. This research provides a mechanistic model by comparing the performances of open storey frame ( Subject frame) with respect to fully infill walls (Baseline frame) using Inter-storey drift ratio and fundamentals frequency as the two parameters. Two types of subject frame have been considering in this research: one with the open storey at the ground floor and other with the open storey at the middle floors. Soft story index (SSI) is an index to identify the extents of damages for a given performances in an existing soft story building. Performances of open storey frame is normalized with respect to Baseline frame at each performance level according to FEMA-356 which will identify SSI . This level will indicate the level of improvement required depending on level of performances that has to be achieved. This shows that the SSI can enhance the capacity to the similar level of uniformly infilled frame. Finally, the implementation, construction and design have applied to one of the frames which shows that the capacity of the retrofitting subject frame has been improved to the capacity like Baseline frame up to the life safety performances. My Imply Soft Story Index (SSI), soft storey frame can enhance its performances at the required level of performances. |
| Year | 2022 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Krishna, Chaitanya |
| Examination Committee(s) | Punchet Thammarak;Anwar, Naveed |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2022 |