In this paper, a fi eld experiment was carried out to study train-induced environmental vibrations. During the fi eld experiment, velocity responses were measured at different locations of a six-story masonry structure near the BeijingGuangzhou Railway and along a small road adjacent to the building. The results show that the velocity response levels of the environmental ground and the building fl oors increase with train speed, and attenuate with the distance to the railway track. Heavier freight trains induce greater vibrations than lighter passenger trains. In the multi-story building, the lateral velocity levels increase monotonically with fl oor elevation, while the vertical ones increase with fl oor elevation in a fl uctuating manner. The indoor fl oor vibrations are much lower than the outdoor ground vibrations. The lateral vibration of the building along the direction of weak structural stiffness is greater than along the direction with stronger stiffness. A larger room produces greater fl oor vibrations than the staircase at the same elevation, and the vibration at the center of a room is greater than at its corner. The vibrations of the building were compared with the Federal Transportation Railroad Administration (FTA) criteria for acceptable ground-borne vibrations expressed in terms of rms velocity levels in decibels. The results show that the train-induced building vibrations are serious, and some exceed the allowance given in relevant criterion.
The wavelet transform and Lipschitz exponent perform well in detecting signal singularity. With the bridge crack damage modeled as rotational springs based on fracture mechanics, the de°ection time history of the beam under the moving load is determined with a numerical method. The continuous wavelet transformation (CWT) is applied to the de°ection of the beam to identify the location of the damage, and the Lipschitz exponent is used to evaluate the damage degree. The in°uence of di®erent damage degrees, multiple damage, di®erent sensor locations, load velocity and load magnitude are studied. Besides, the feasibility of this method is veri¯ed by a model experiment.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.