In this paper, the impacts of environmental vibration on precision instruments as well as the vibration allowances of precision instruments are introduced firstly. Then the integrated model of a high-rise building is established, and the vibration responses of the floor where a precise instrument is fixed are calculated by inputting micro-vibration loads. The passive control method is used by putting several lead rubber bearings at the bottom of instrument and at the bottom of building separately, and the isolated vibration responses are calculated and analyzed. Some valuable conclusions are obtained by comparing the vibration responses of isolation system and non-isolation system with acceptable values according to the environmental vibration codes for precise instruments.

In this paper, based on the finite element program ANSYS, the model of a simply supported railway bridge with and without isolation using lead rubber bearing is established. Seismic response time-history analyses of the bridge subjected to high-level earthquakes are carried out considering and not considering train live loads. Through the comparison and analyses of the results, the effects of train live loads on seismic calculation of non-isolated railway bridges and isolated railway bridges are obtained. The results of the research will support the further study on seismic design and isolation design of simply supported railway bridges.

Based on the finite element program SAP2000, 120 models of eight different piers with different lead-rubber bearings (LRB) are established. The seismic response analyses of piers isolated by LRB in axial direction of the bridge are carried out under the excitations of seven earthquake waves. The calculations of seismic responses of the piers with and without isolation are implemented by using dynamic time-history analysis method, and the comparison of the results is given out. Considering the isolation ratio of the moment at the bottom of pier as observation samples, the variances of the three LRB mechanical parameters are analyzed. Furthermore, the ability of the parameters of LRB to adjust the seismic response of different piers is discussed. The analysis results show that all the mechanical parameters of LRB have significant effect on the isolation ratio of the moment at the bottom of pier, and the parameters of LRB can adjust the seismic forces of the isolated piers whose height difference is less than 30 meters to be almost equal. This paper provides some valuable references for the further study of isolation design for railway bridges.

In order to study the mechanical performance of Reactive Powder Concrete (RPC) used for structure engineering, 38 series of RPC specimens are fabricated, cured, tested and analyzed. There are 5 sets of specimens are fabricated for each actual site structure engineering. The compressive strength, flexural strength and elastic modulus are tested according to the specimens and the compressive strength is tested with different age time. All the specimens are steam cured with the same situation as the structure. According to the test result, the compressive strength of RPC is up to 80MPa 3days after it is cast and the compressive strength is higher than 120MPa 15days later. The average flexural strength of RPC is 19.4MPa and the elastic modulus is 45.15GPa. The tested results show that the mechanical performance of RPC can satisfy the engineering requirement. The mixing proportion and the curing system can be used for engineering design and construction.

Based on optimization theories, considering soil-structure interaction and running safety, the optimal design model of the seismic isolation system with lead-rubber bearings (LRB) for a simply supported railway beam bridge is established by using the first order optimization method in ANSYS, which the parameters of the isolation bearing are taken as design variables and the maximum moments at the bottom of bridge piers are taken as objective functions. The optimal calculations are carried out under the excitation of three practical earthquake waves respectively. The research results show that the ratio of the stiffness after yielding to the stiffness before yielding has important effect on the structural seismic responses. Through the optimal analysis of isolated bridge system, the optimal design parameters of isolation bearing can be determined properly, and the seismic forces can be reduced maximally as meeting with the limits of relative displacement between pier top and beam, which provides efficient paths and beneficial references for dynamic optimization design of seismic isolated bridges.