Seismic response of asymmetric rectangular blocks in high-rise buildings | |
| Author | Sivapalan, Sivaram |
| Call Number | AIT Thesis no.ST-21-14 |
| Subject(s) | Earthquake hazard analysis Buildings--Earthquake effects High-rise apartment buildings |
| 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 |
| Series Statement | Thesis ; no. ST-21-14 |
| Abstract | When subjected to earthquake, the primary response modes of rigid free-standing rectangular blocks (non-structural components) are sliding and rocking. However, the most damaging response mode is rocking due to its possibility of overturning, which may cause fatal accidents. This study experimentally and analytically examines the rocking behaviour of typical asymmetric building blocks located at different floor levels in four types of high-rise buildings (40, 33, 23, 12 story buildings). Eight ground motions are selected for moderate to high seismic hazard zone. For symmetrical blocks, an analytical model used was based on the governing equation of rocking motion established by Housner G. (1963). This governing equation is widely used and well known in the literature. In this study, Housner’s analytical model was further improved for asymmetrical blocks, and the computer program (MATLAB SIMULINK) was written to solve the developed governing equation. It was used to predict the rocking and overturning behaviour of rigid, rectangular, asymmetrical building blocks under horizontal acceleration. The accuracy of the computer program was checked by comparing its results with the analytical results proposed by Makris and Roussos (1998) and Wittich (2015). Moreover, our asymmetrical analytical model can still predict the overturning PGA (Peak Ground Acceleration) or PFA (Peak Floor Acceleration) for books inside the bookshelves. This comparison shows that our computer program is accurate enough and can be used in further analysis. To verify the reliability of the computer program, experimental tests were conducted on a 1.0×1.2 m uni-axial shaking table at the Asian Institute of Technology, Bangkok. For symmetric block, the conventional filling cabinet with a slenderness ratio (B/H) of 0.13 and For asymmetric block, bookshelf with a slenderness ratio (B/H) of 0.14 were selected as the test specimens used in this study. Moreover, contents (books) inside the bookshelf were tested for four different cases (without books, packed books inside, loosen books inside, loosen books outside). The comparisons between the experimental and analytical results under a total of 95 ground and floor motions were made, and an acceptable agreement was found between these two. By applying for the computer program, the rocking and overturning behaviours of typical building contents with sizing parameter (R) ranging from 0.5-2.0 m, critical angle ({u1D6FC}) of 3°-20° and critical angle ratios ({u1D6FC}1/{u1D6FC}2 ) of 1 - 2.25 were examined under the floor accelerations (ETABS) for four case study buildings. For developing fragility curves, an analytical model was simulated for 3456 cases, including eight ground motions, floor motions in four different buildings, 16 different symmetrical blocks, and 32 different asymmetrical blocks. For every 3456 cases, seismic accelerations are considered from zero up to the overturning by increasing 0.001g (total nearly 500,000 simulations). The universal fragility curves for several limit states (LSs) were created in this study by using the normalized peak angle of rotation ({u1D703}/{u1D6FC}2 ) as the demand parameter and a physically motivated intensity measure based on the PFA, ({u1D443}{u1D439}{u1D434}/({u1D454}.tan {u1D6FC}). The proposal of developing these fragility curves was to improve the estimation method of the damage of the building blocks against future earthquakes. One of the main findings of this paper is that when comparing the rocking responses in terms of fragility curves, the typical building blocks are more vulnerable to the characteristic of floor motion (narrow-band excitation) rather than the characteristic of ground motion (wide-band excitation) in a high-rise building. |
| Year | 2021 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ST-21-14 |
| 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) | Pennung Warnitchai; |
| Examination Committee(s) | Punchet Thammarak;Anwar, Naveed; |
| Scholarship Donor(s) | AIT Alumni SEC'88;Asian Institute of Technology Fellowship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2021 |