Numerical Investigation on the effects of local damage to the dynamic properties of buildings using limited vibration data

• Main Author: Caringal, Kristian Lawrence Villar
• Format: text
• Language: English
• Published: Animo Repository 2015
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/4953
• Institution: De La Salle University

The numerical of accelerographs for high-rise buildings offers a potential for structural health monitoring. Due to costly and time consuming inspections when a structure is damaged, many researchers are engaged in studying and developing different techniques on how to use and maximize data from recorded accelerographs and apply it to different types of structures. The National Structure Code of the Philippines (NSCP 2010) mandates that every building over 50 m in height shall be provided with not less than three approved recording accelerographs. The challenge in structural health monitoring and damage detection is how to use the limited number of sensors on a building to assess the condition of the structure. The study investigates strategies on how the limited number sensors can be used effectively so that the the benefits from this costly investment can be maximized. Among these benefits are using the vibration data to provide a warming signal on building damage to a certain relevant change in dynamic properties. In addition, the optimum location for the middle accelerometer is also to be investigated. A damage detection strategy was applied to a shear-building model of a structure. Simulations of application of different levels of isolated local damage to the different floors were done to determine the corresponding dynamic properties and to observe the sensitivity of the dynamic properties to local changes. Dynamic condensation was also applied to the model to portray limited vibration data. It was observed that the supposed to be middle accelerometer should be placed at 3/4 of the total height of the building. By doing so, it can provide more correct frequency readings as compared to placing it exactly at the mid height of the building. Furthermore, it was examined that the results from the condensed 2 DOF model resulting into the two lowest natural frequencies in the structure can only be used in detecting the damage from the first unto the fifth floor in the building. With that, a change of 5% in the frequency can mean up to a 50% local damage to the stiffness in a building even with limited vibration data and provide warning signals as part of structural health monitoring.