Research On Environmental Vibration Induced By Urban Elevated Road

The research work is financed by National Natural Science Foundation Project(No 50578046) titled by"Vibration transmit laws of the adjacent building induced by highway road and vibration-reduction technologies". On one hand, generation mechanism and propagation laws for urban elevated road-induced environmental vibration have been investigated systematicaly through theoretical analysis and experimental methods. On the other hand, based on existing seismic control technology, vibration-reduction control technologies in buildings are studied, which can effectively reduce harmful effect on human living environment, building structures and performance of precise instruments due to environmental vibrations. This research work produced all-important theoretical significance and broad application prospects. The main theoretical analyses, field research and experimental studies are carried out as follows:1 Vibration source of urban highwy-induced environmental vibration system is studied. First, vehicle queue simulation method has been proposed according to exponential distribution. Modal analysis for a multi-span beam with intermediate flexible constraints and different boundary conditions has been suggested. Each span of continuous beam has different span, different stiffness and different mass per unit length, which is assumed to satisfy Euler beam theory. Afterwards, considering the coupling dynamic effect of vehicle-bridge-pier, time-history analysis and evolutionary random vibration theory for the vibration source are presented.2 Propagation of vibration in layered soil is investigated. Theoretically, based on deformation compatibility, equilibrium conditions between two adjacent layers, dynamic analysis of 3-D layered under moving vehicle loads are proposed. Numerically, acceleration as input directly, finite element analysis model of vibration propagation in layered soil is proposed. Comparison between the numerical and measurement analysis results of vibration propagation indicated that finite element analysis can be used as qualitative method for the influence of environmental vibration on city area.3 The effect of environmental vibration on surrounding building structures are studied. First, based on measured vibration wave and self-compiling program, dynamic behavior of frame structure models are analyzed in time and frequency domain. Secondly, by modeling measured gymnasium structure with ANYSYS, comparison between the calculated and measurement results of gymnasium vibration indicated that vibration characteristics of building structures can generally be reflected by numerical analysis result. Numerical analysis in ANYSYS can be used as a method for the qualitative and sensibility analysis of building structure influenced by environmental vibration4 Due to random properties of environmental vibration propagation chain, stochastic analysis method for urban environmental vibration system induced by highway load is presented. The power spectral density (PSD) of traffic-induced force acting on the ground through the viaduct systems, ground dynamic response and structure vibration are derived.5 According to the limitation of theory methods and numerical simulation, environmental vibration induced by urban highway road is measured in field, including highway road vibration, ground vibration propagation and building vibration. Environmental vibration test data are analyzed in time and frequency domain. Mathematical statistics methods were employed to establish the empirical attenuation formula of vertical ground vibration. Comparing with the limits in"Standard of Environmental Vibration in Urban Area"and"Standard of Limit and Measurement Method of Vibration in the Room of Residential Buildings", most of field measurement results of environmental vibration induced by urban highway road satify the required national standards.6 Based on base isolation technology, energy dissipation technology and Tuned Mass Dampers (TMD) control technology, the effectiveness of these vibration-reduction methods in buildings due to environmental vibration is presented. First, 3-D base isolation device is developed, which is a combination device of Lead Rubber Bearing (LRB) and Lead Dish-Spring Bearing (LDSB). Mechanical property testes of 3-D base isolation device are performed. Second, numerical analysis results demonstrated that the vibration reduction effectiveness of base isolation technology is obvious, energy dissipation is certain, and TMD is obviously affected by the environmental vibration used as input.