Buildings with large column-free floors or long-cantilevered structures can be susceptible to annoying vibrations due to everyday occupants’ activities such as walking. Computer modeling and analytical representation of building structural properties to predict the floor response subjected to excitations due to human activities are important issues that require further studies. Vibration testing and analysis of built structures can assist in more accurate estimation of structure dynamic properties. This paper presents the results of the modal testing conducted on an office building floor and analysis of the collected vibration measurements. It compares these results with the structural response using computer analyses. It also presents a sensitivity study to assess the importance of various structural parameters on the floor dynamic response. From the results presented, it is concluded that for the structure used in this study the raised flooring and nonstructural elements acted mainly as added mass and d...

This paper discusses the development of virtual structural analysis program (VSAP). This is a virtual environment (VE) based structural analysis system developed through a collaborative effort between the School of Architecture + Design and the Department of Computer Science at Virginia Polytechnic Institute and State Univ. (Virginia Tech). The VSAP was developed by linking a visualization routine using the simple VE library and a structural analysis software, the PC-SAP4. Details of the design of four user interfaces for the VSAP are presented. These user interfaces are: the immersive pen and tablet interface, the desktop interface, the portable immersive interface, and the cave automatic VE immersive interface. Usability studies for each interface were conducted. Results of these studies indicated that the users of VSAP were highly satisfied with the experience. In addition, all the developed interfaces were found to be successful for their specific application.

People are generally very sensitive to unexpected vibrations. Very small levels of building floor movements due to activities such as walking can become annoying to occupants. Accurate prediction, evaluation, and assessment of vibrations can greatly assist engineers and architects to design cost-effective building structures without such problems. In an attempt to clarify some of the issues related to this common serviceability problem, this paper presents a study of the various parameters used for the evaluation and assessment of building vibrations. Provisions of several current standards and design guides commonly used in North America and U.K. to evaluate and assess building vibrations as related to human perception and comfort are reviewed. These provisions are then applied using the vibrations measured during a number of walking tests conducted on a large cantilevered office building floor. Based on the results of this study, it is concluded that the vibration dose value (VDV) recommended by some st...

Innovative architectural designs create new challenges for structural designers such as annoying vibrations because of the everyday occupant activities such as walking. The designer needs to predict the excitation levels to evaluate the structural response and assess the resulting vibrations for acceptable human exposure. This paper uses a long-cantilevered office building structure to study the floor response subjected to various measured and Fourier series-based forcing functions representing human walks suggested in standards, design guides, and research studies. In addition, the vibration evaluation parameters proposed by several standards are computed and compared by using computer analyses and field measurements. For the majority of the cases studied in this paper, use of the Fourier series-based forcing functions resulted in an overestimation of the structural response. In addition, the in-place marching excitations to represent walking recommended in some design guides can grossly overesti...

This paper offers an experimental robustness analysis of a semi-active tuned vibration absorber (TVA) subject to structural mass off-tuning, which occurs frequently in practical applications of TVAs. One of the critical problems of a conventional TVA is off-tuning or miss-tuning because off-tuned TVAs may amplify the vibrations of the primary structure. This study intends to evaluate how well semi-active TVAs are able to adapt to structural mass changes (mass off-tuning) as compared with passive TVAs. To this end, a test apparatus was built to represent a two-degree-of-freedom structure model coupled with a TVA. The semi-active TVA considered in this study employed a magneto-rheological (MR) damper as its damping element to enhance overall performance. Using this test apparatus, a series of tests were conducted to identify the optimal tuning parameters of the TVAs. After obtaining each TVA’s optimal tuning parameters based on equal peak transmissibility criteria, the mass off-tuning tests were then performed on the optimally tuned TVAs. In order to off-tune the system, the mass of the primary structure varied from $−19%$ to $+19%$ of its nominal mass using a set of steel plates. Overall, the experimental results show that the semi-active MR TVA outperforms the passive TVA in reducing maximum vibrations. Moreover, the results show that the semi- active TVA is more robust to changes in the primary mass (mass off-tuning) The results further show that the semi-active MR TVA offers larger performance gains as the structure mass increases.