Influence of Non-Structural Elements on Dynamic Response of Multi-Storey Rc Building to Mining Shock
In the paper the results of calculations of the dy namic response of a multi-storey reinforced concrete buil ding to a strong mining shock originated from the main region of min ing activity in Poland (i.e. the Legnica-Glogow Copper District) ar e p esented. The representative time histories of accelerations regi st red in three directions were used as ground motion data in calcu lations of the dynamic response of the structure. Two variants of a numerical model were applied: the model including only structural e lements of the building and the model including both structural an d non-structural elements (i.e. partition walls and ventilation duct s made of brick). It turned out that non-structural elements of multi-st orey RC buildings have a small impact of about 10 % on natural freque ncies of these structures. It was also proved that the dynamic res pon e of building to mining shock obtained in case of inclusion of al l non-structural elements in the numerical model is about 20 % small er than in case of consideration of structural elements only. The p rincipal stresses obtained in calculations of dynamic response of mul ti-storey building to strong mining shock are situated on the level of about 30% of values obtained from static analysis (dead load). Keywords—Dynamic characteristics of buildings, mining shocks , dynamic response of buildings, non-structural eleme nts
Vibration serviceability assessment of office floors for realistic walking and floor layout scenarios: Literature review
Over the last two decades, office floors have been built progressively lightweight with increasing spans and slenderness. Therefore, vibration performance of office floors due to walking dynamic loads is becoming their governing design criterion, determining their size and shape, and therefore overall weight and embodied energy of the building. To date, floor design guidelines around the world recommend walking load scenarios in offices featuring some or all of the following standard characteristics: (a) walking loads are assumed to be periodic dynamic excitation represented by the Fourier series, including harmonics corresponding to up to the first four integer multiples of the pacing frequency of which at least one is exciting the floor at a resonant frequency and (b) single person walking. However, the literature surveyed provides evidence that such assessment methodology is potentially an over-simplification which does not reflect real walking load scenarios, since crucial features of the floor vibration source, path and receiver are missing. First, in terms of vibration source, realistic scenarios need to feature (a) moving rather than stationary walking forces, (b) stochastic nature of human gait, (c) simultaneous multi-person walking and (d) human–structure interaction. Second, for the transmission path (i.e. office floor structure), two features are needed to consider: (a) realistic office floor layouts and (b) presence, or absence, of non-structural elements. Finally, for the vibration receivers (i.e. floor occupants), (a) vibrations calculated at floor locations occupied by users (instead of at the potential highest response location which may not be occupied), (b) actual period over which occupants feel vibration due to such excitation and (c) assessment of vibration levels based on their probability of occurrence. This study therefore addresses these seldom considered but increasingly important features and discusses realistic approaches to floor design for vibration serviceability.
Full-scale measurements of the dynamic characteristics of buildings in the UK
Abstract This paper is concerned with the dynamic characteristics of buildings, especially with the measurement of damping. It describes the methods employed by BRE for testing buildings and presents reliable methods of assessing damping from forced vibration tests. Other methods of determining damping are also mentioned and some of their limitations discussed. Data from measurements on 16 buildings in the UK are then given. Next the subject of soil-structure interaction is considered, the results from four buildings are presented and the effects of the interaction evaluated. Finally the subject of non-linear behaviour is discussed and measured characteristics from vibration tests are considered. Because the range of amplitudes of vibration measured on buildings is limited, examples from tests examining the non-linear characteristics of two other structures are presented.