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The fabrication of optical waveguide couplers involving tapered layers of SiO(2) is discussed. Details of the photolithographic fabrication processing sequence are presented. This process utilizes carefully controlled etchant undercutting and has been found to be quite reproducible. It has allowed fabrication of tapers having changes in Sio(2) thickness of 1.0,microm over lengths of 55-75 microm. Results are presented which demonstrate taper transverse uniformity for distances of over 600,microm. The smoothness and gradual nature of the tapers are apparent in scanning electron microscope pictures of a taper cross section.

This paper is concerned with the inspection and evaluation methods on dynamic performance of highway bridges under moving vehicular loads. The background and development process of the existing specifications are stated and discussed. Up to now, four specifications or drafts for approval related to dynamic performance inspection and evaluation have been published. The deficiencies of the existing specifications are discussed and the differences among them are compared, including dynamic loading test methods, data processing, and evaluation criteria. Finally, some key research topics about the inspection and evaluation methods on dynamic performance of highway bridges are proposed.

Aluminum/Polytetrafluoroethylene (Al/PTFE) active materials have the dual characteristics of strength and activity. When acting on the target, it penetrates first and then deflagration, so as to enhance the damage effect on the target. Based on the traditional formula of Al/PTFE (26.5%/73.5%), the reinforced Al/PTFE active materials are prepared by cold pressing sintering and rapid cooling process. The static and dynamic compression experiments are carried out on this material. Based on the compression experiment data, the Zhu‐Wang‐Tang (ZWT) constitutive model parameters of the reinforced Al/PTFE active materials are fitted. The self‐made ZWT constitutive model subroutine is embedded into ABAQUS by the user material subroutine interface (VUMAT), and the numerical simulation is carried out in the range of medium strain rate (1400–3300 s−1). The accuracy of the parameters of the constitutive model is verified by the combination of experiment and numerical simulation. The results show that the reinforced Al/PTFE materials have better mechanical properties under dynamic loading than the traditional formula Al/PTFE. When the strain rate is 1400 s−1, the maximum stress of the reinforced Al/PTFE materials is 54 MPa, which is 1.5 times the strength of the traditional formula Al/PTFE; when the strain rate is 2800 s−1, the maximum stress of the reinforced Al/PTFE materials is 100.3 MPa, which is 1.9 times that of the traditional formula Al/PTFE. In the range of strain rate from 1400 to 2800 s−1, the time‐history curves of true stress, true strain, and strain rate obtained by numerical simulation are in good agreement with the experimental results. It is extrapolated to the loading strain rate of 3300 s−1, and the numerical simulation results are still in good agreement with the experimental results. The compressive ZWT constitutive model of reinforced Al/PTFE active materials obtained in this paper is reliable and can well describe the dynamic mechanical properties of the material at medium strain rate (1400–3300 s−1).

To address the drawback of comfort evaluation on Highway Bridges due to moving vehicular loads, a large-span continuous girder bridge, namely Yilan Songhua River Highway Bridge, is studied in detail. The pedestrians comfort and riding comfort of the selected bridge under both single-vehicle and multi-vehicle are analyzed by our computer programs VBCVA (vehicle-bridge coupled vibration analysis) which is based on modal synthesis method and VCE (vibration comfort evaluation) which is based on existing common evaluation criteria. The peak accelerations of vehicles and the bridge are significantly influenced by the increase in bridge surface roughness as speed increases. Pedestrians acceleration induced by truck is larger than that induced by car. Except at the abutment span where the resonance speed is lower than other spans, the comfort of pedestrians at different locations of the mid-span are practically the same for various speeds. The riding comfort influenced by the truck on adjacent lane is dependent on the relative value between the dynamic response of the bridge and its roughness. For continuous girder bridges, because of the smaller dynamic response induced by the truck on adjacent lane compared to that induced by the roughness of the lane itself, the influence between adjacent lanes can be ignored. Finally, it is shown that the pedestrian comfort and riding comfort of the newly built Yilan Songhua River Bridge could meet the existing requirements in normal operation.