【正文】 ributed to each of a number of subsystems according to their reso nant energy capacity resulting in an estimate of the mean squared vibration velocity on each susbsystem. For parts of the structure such as the wooden walkways to the side of the tracks on the Burgdorf Bridge, additional works of subsystems can be added to the model that are excited by the velocity of particular susbsystems of the main work. The bridge bearings and piers are not important for the noise radiation. For the track, the rail support stiffness is an important parameter. The bined roughness of the wheel and rail running surfaces excites the wheel and rail into vibration according to their dynamic properties. Models for the rolling noise emitted by the wheel and track are well established [4, 5]. The way in which the track is assumed to transmit energy to the SEA model of the bridge is an important aspect of the calculation. For the current bridge, a model of the rail coupled via a con tinuous springmassspring support to the longitudinal beam of the bridge has been used up to the railonsleeper resonance frequency. Above this frequency the force 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 5 from the track is assumed to drive the local input mobility of the longitudinal beam. The latter is based on an approximate formula for an Isection beam [6]. The sound power is calculated from the vibration velocity of each ponent via simply calculated radiation ratios for each plate subsystem. Simple propagation calculations are then used to estimate the sound pressure level at particular receiver locations. The principles and results of the analysis were piled in a report for Swiss Railways [7]. In the case of the Burgdorf Bridge, the steel sleepers will have a significant effect on the track decay rates and provide an additional radiating ponent. These effects have been accounted for with a specially constructed track model. This includes the modal behaviour of the wooden and steel sleepers modelled as beams. The effect on the decay rates on noise is calculated as correction to the prediction (see [8]). Parameters Derived from Measurements on the Bridge Using Service Trains Fig. 2(a) shows the measured vertical direct receptance at the railhead. Although the measurement quality is poor, especially below 300Hz, the main resonance peak due to the stiffness of the rail support can be clearly seen. The dashed line on Fig. 2(a) shows the calculated receptance using a support stiffness of 240MN/m and a mass per sleeper end of 28kg. In Fig. 2(b) the calculated decay rates are shown along with the decay rates measured by SBB according to the method described in reference [8]. In the measurements of the decay rate responses up to a distance of from the excitation have been used. The minimum decay rate measureable with this length of baseline is [8]. The measured decay rate is well above this. 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 6 of measurement and calculation: left side, vertical point receptance of the rail。 Fax: +41 (0)51 220 5014 2 University of Southampton, ISVR, Highfield Southampton, SO17 1BJ, Southampton, UK Tel.: +44 (0) 2380 593224。 中文 3387 字 本科畢業(yè)設(shè)計(jì) 外文文獻(xiàn)及譯文 文獻(xiàn)、資料題目： Structural Design of Reinforced Concrete Sloping Roof 文獻(xiàn)、資料來(lái)源： 網(wǎng)絡(luò) 文獻(xiàn)、資料發(fā)表（出版）日期： 院 （部）： xxx 專 業(yè)： xxx 班 級(jí)： xxx 姓 名： xxx 學(xué) 號(hào)： xxx 指導(dǎo)教師： xxx 翻譯日期： xxx畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 2 外文文獻(xiàn)： Experimental and Theoretical Analysis of Railway Bridge Noise Reduction Using Resilient Rail Fasteners in Burgdorf, Switzerland . K246。stli1, . Jones2, and . Thompson2 1 Swiss Federal Railways SBB, IFWPS, Schanzenstr. 5 CH3000 Bern 65, Switzerland Tel.: +41 (0)51 220 4699。 Fax: +44 (0) 2380 593190 Summary The increased noise level as trains travel over bridges is, in many situations, a source of disturbance for nearby residents. As well as the rolling noise radiated by the wheel and track, the vibration generated at the wheelrail interface also propagates into the bridge structure and the vibration response of the ponents of the bridge is an important extra source of noise pared with tracks atgrade. Vibration isolation of the bridge structure from the rail is therefore used to reduce noise. This often takes the form of resilient rail fasteners. Two different elastic rail fastenings were therefore tested on a twin track bridge by the Swiss Railways (SBB). The bridge over the river Emme at Burgdorf, is a ballastless steel bridge with timbers between the rail fastener and the bridge. Hanging steel sleepers have been added between the wooden sleepers on which the track is 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文