Applied Mechanics and Materials Vols. 501-504

Abstract: Shear lag effect of box girders under static, transient dynamic load and harmonic dynamic load has been studied, respectively, through finite element method. Shear lag effects under different load conditions were compared and dynamic loading influence on shear lag was analyzed. The results show that the dynamic load has great influence on shear lag of thin box girder that can not be neglected. During the research, the eyesight was transfer from the conventional static load to the dynamic load to study the shear lag problem of box girder. The research conclusions will be useful for the design and construction of bridges and will enrich the design theory of box girder.

Abstract: Unbonded tendon stress calculation of unbonded precast concrete structure is defferent from prestressed concrete structure, as tendon strain caused by the external load is not in accordance with relevant sections of the concrete strain obtained. As the deformation of unbonded tendons are not subject to the deformation of plane-section assumption, therefore, arise due to external loads of unbonded tendon stress calculation is more complex. In this paper, based on theoretical analysis and derivation, the pre-stress deformation of the unbonded steel stress formula was given, this can provide more scientific basis for the stress Analysis of unbonded precast frame structure.

Abstract: A vertical isolation device was designed and based on test requirements in this paper, which adopt disk spring with external guide sleeve. Through reasonable designing, this device can meet the requirements of stiffness and bearing capacity, etc. Single disk spring and properties of vertical isolation device were analyzed by finite element software ANSYS. The numerical simulation and the theoretical solution of single disk spring are basically coincident when small deformation. Even the deformation is large and there only are minor differences. The contact problems between disk springs, disk group and external sleeve, should be taken into consideration. The comparisons for hysteretic curve between numerical simulation and experiment result of vertical isolation device shows that their stiffness and energy dissipation capacity are very close, and the precision of the model can satisfy the requirement of numerical analysis and engineering application.

Abstract: To the Yangtze River a long-span transmission tower as an example, this paper makes a comparative analysis on the davenport wind spectrum and kaman wind spectrum, using two different wind spectrum calculation of wind-induced response of the structure. Obtained the conclusions that kaman wind spectrum of considering vertical correlation get greater wind-induced response in a large span transmission tower engineering.

Abstract: It has great significance to ensure the safety of bridge structure by using information technology to monitor the bridge dynamic deformation and find out problems in time, besides, it is more effective to make analysis of the bridge by using grey theory model. The combination of the two methods could avoid the observation error, and play an active role in improving the safety and reliability of bridge.

Abstract: The slope monitoring is the basis of slope management and ensure the safety of slope, is regarded year by year. This paper mainly introduced several kinds of more advanced, more commonly used slope monitoring method, elaborated the key from the principle and advantages and disadvantages, and analyzed the application of open-pit mine monitoring equipment from the Huogeqi mining area. It will have certain reference significance for selection of open-pit mine slope monitoring method.

Abstract: Accidents in the tunnel construction happen frequently. In order to provide a safety work and monitoring environment, 3D monitoring alarm warning system in tunnel construction had been developed based on database technology, communication technology, Creator, Vega Prime and OpenGL. The system provides a variety of browse modes of 3D simulation view for construction personnel to monitor construction site. It also provides the 3D interactive operation, monitoring data entry, query and analysis, construction progress simulation and automatic alarm warning and trend prediction. The system improved the safety status analysis of visual construction site monitoring. In addition, it also improved the construction progress and provided a stable and reliable technical support for safety construction of the first phase of Xiamens airport road Tender JC2 to JC3.

Abstract: This paper proposes a methodology on simultaneous identification of substructure excitation and damage. Structural damages are simulated by virtual distortions which are computed together with unknown excitations using the measured responses through the intact isolated substructure model; the damage extent and type is then recovered by a comparison of the virtual and actual distortions. Unknown factors are reduced greatly which allows the method to be applied on practical complex structure. The computational cost is cutoff sharply. A damaged nonlinearity aluminum beam is used in the experimental verification. Both load and damage are successfully identified.

Abstract: Ground Penetrating Radar (GPR) is a high efficiency technology to detect the cylindrical medium in the concretes material. The electromagnetic wave is incidental to double-rebar, and measures the reflection signal behaviors from energy zone. The results from the reflection signal of electromagnetic wave of the reinforcement concretes allow evaluating the radius of double-bar (1.6cm, 1cm). A physical model can effectively measure the radius of double-bar by the result of electromagnetic wave reflex behavior analysis. The results indicate that, this techology is capable of estimating the reinforcing double-bar radius to within 6%.

Abstract: This paper presents a static-based method for damage identification in the simply supported beam structure using the incomplete measured static displacement parameters. The presented method makes use of the singular value decomposition of structural static displacement change, which is obtained by the static test of structure. It has been shown that structural damage can be detected by the number of the non-zero singular values of the static displacement change. The significant advantage of the proposed method is that it is economical in computation and is simple to implement. A simply supported beam structure is analyzed as a numerical example to verify the present method. Results show that the proposed method performs well even if the measurement errors inevitably make the damage assessment more difficult. It has been shown that the presented static-based methodology may be a promising tool to be used by research groups working on experimental damage detection.