Numerical evaluation of seismic screening in mid-rise buildings using the operational modal flexibility | |
| Author | Paweeta Wintachai |
| Call Number | AIT Thesis no.ST-25-23 |
| Subject(s) | Buildings--Earthquake effects Earthquake resistant design--Thailand Structural analysis (Engineering) Modal analysis |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Structural Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | This study proposes a non-destructive seismic screening index to distinguish code compliant from non-compliant reinforced-concrete (RC) buildings. Operational Modal Analysis (OMA) is used to extract natural frequencies and mode shapes under ambient vibration, from which the modal flexibility matrix is reconstructed. Its spectral norm the Flexibility Matrix Norm (FMN) forms a dimensionless FMN index defined as the ratio between a building’s FMN and that of a seismic-compliant reference frame. Because flexibility is the inverse of stiffness, the index serves as a direct proxy for global lateral stiffness, with values near one indicating compliant stiffness and larger values signalling possible non-compliance.A representative mid-rise RC frame is evaluated under four scenarios: a seismic compliant baseline, a soft-story seismic design, a gravity-type building, and a gravity type soft story. To reflect realistic field conditions, the study examines the impact of limited instrumentation (three vs. five sensors) and the number of retained modes, and also correlates FMN behaviour with stiffness degradation observed from monotonic pushover analysis.Results show that the FMN index clearly distinguishes compliant from non-compliant cases and increases consistently with structural drift. Mode 1 provides most of the sensitivity, while Mode 2 adds only minor refinement. A three-sensor setup still preserves the correct ranking because the first mode is smooth and easily interpolated, although higher modes are only approximated. Overall, the FMN index offers a practical, field-ready, non-destructive screening tool for prioritizing buildings for detailed seismic evaluation, with field validation identified as the next development step. |
| Year | 2025 |
| 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) | Krishna, Chaitanya |
| Examination Committee(s) | Thanakorn Pheeraphan;Pennung Warnitchai;Raktipong Sahamitmongkol |
| Scholarship Donor(s) | Royal Thai Government;AIT Scholarship |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2025 |