ABSTRACT: The excessive vibration in a building due to along-wind and across-wind excitations can affect the health and/or interrupt the activities of the inhabitants. Perception curves, in terms of mean peak acceleration or standard deviation of acceleration have been developed and adopted in codes as serviceability criteria for designing buildings. Some of these criteria do not incorporate the uncertainty in structural properties and wind characteristics. The main purpose of this study is to carry out a comparison between some of the major serviceability criteria for designing buildings and to estimate the reliability level for structures designed according to such perception curves, incorporating the uncertainty in structural properties, wind characteristics, and in the human perception of motion. For the analyses, the probability distribution of the peak acceleration response proposed by Davenport is adopted, and the random vibration approach is employed to determine the maximum response of a structure. Results of the analysis indicate that the reliability (the probability that the wind-induced vibration of a designed structure is not perceived within a service period) associated with structures designed according to different serviceability criteria is not the same, even if the structures are designed for the same perception level. KEY WORDS: Wind; Vibration; Acceleration; Perception Curves; Reliability. 1 INTRODUCTION The design of tall buildings includes the consideration of an ultimate limit state and a serviceability limit state. Even if the ultimate limit state is satisfied, tall buildings can experience excessive vibration under wind loading. This excessive vibration can deteriorate health of the inhabitants of the buildings, disrupt the activities or cause discomfort. Some studies on the acceleration limits for human comfort levels were carried out in the 70’s by Van Koten, Chen and Chang [2, 3, 4]. These studies related acceleration levels with subjective descriptors. From these studies, it is possible to identify levels of perception of acceleration at about 15 milli- g. To take into account the excessive vibration during the design stage, codes and/or standards propose the use of criteria to limit the excessive wind-induced motion [5, 6, 7]. The criterion proposed by ISO10137 [5] suggests the use of the mean peak acceleration, as a function of the frequency of vibration, to limit the discomfort level and disruption of tasks of inhabitants of buildings. The NBCC [6] also employs the mean peak acceleration as a perception limit; this criterion is independent of the frequency of vibration. The AIJ [7] suggests the use of perception curves with different perception levels; this criterion is frequency dependent and uses the mean peak acceleration to limit the wind-induced motion. All these criteria consider a 1-year return period value of wind speed, except for the NBCC [6] that considers a 10-year return period of wind speed. Figure 1 presents a comparison of the three criteria described above. All the curves correspond to a 10-year return period value of the mean wind speed. Figure 1. Limits of perception. It is observed in Figure 1 that the perception levels suggested in ISO10137 [5] and the NBCC [6] depends on the use of the structure, while the criterion suggested by the AIJ [7] considers the use of curves associated with different probability of perception levels. The serviceability criteria suggested by ISO10137 [5] and the AIJ [7] is employed to estimate the reliability levels for Wind-induced vibration: a serviceability study Adrián Pozos-Estrada 1 , Isaac F. Lima Castillo 1 , Roberto Gómez Martínez 1 , J. Alberto Escobar Sánchez 1 1 Instituto de Ingeniería, Universidad Nacional Autónoma de México, Circuito Escolar s/n, Ciudad Universitaria, Delegación Coyoacán, México D.F., C.P. 04510 email: [email protected], [email protected], [email protected], [email protected]Proceedings of the 9th International Conference on Structural Dynamics, EURODYN 2014 Porto, Portugal, 30 June - 2 July 2014 A. Cunha, E. Caetano, P. Ribeiro, G. Müller (eds.) ISSN: 2311-9020; ISBN: 978-972-752-165-4 1431
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Wind-induced vibration: a serviceability studypaginas.fe.up.pt/~eurodyn2014/CD/papers/200_MS07_ABS... · 2014-05-16 · ultimate limit state and a serviceability limit state. Even
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ABSTRACT: The excessive vibration in a building due to along-wind and across-wind excitations can affect the health and/or
interrupt the activities of the inhabitants. Perception curves, in terms of mean peak acceleration or standard deviation of
acceleration have been developed and adopted in codes as serviceability criteria for designing buildings. Some of these criteria
do not incorporate the uncertainty in structural properties and wind characteristics. The main purpose of this study is to carry out
a comparison between some of the major serviceability criteria for designing buildings and to estimate the reliability level for
structures designed according to such perception curves, incorporating the uncertainty in structural properties, wind
characteristics, and in the human perception of motion. For the analyses, the probability distribution of the peak acceleration
response proposed by Davenport is adopted, and the random vibration approach is employed to determine the maximum
response of a structure. Results of the analysis indicate that the reliability (the probability that the wind-induced vibration of a
designed structure is not perceived within a service period) associated with structures designed according to different
serviceability criteria is not the same, even if the structures are designed for the same perception level.