Applied Mechanics and Materials Vols. 405-408

Abstract: The paper deals with the design of steel structure of the temporary footbridge, intended especially for the usage in the construction site for pedestrian and bicycle traffic. In the period of last two years, on the authors workplace, in the co-operation with the mounting company, the new type of steel footbridge is being developed. Within this development the attention is, among others, paid to the structural design, in particular to the harmonization of static solution and structural detailing, to achieve the efficient design. In the course of solving this problem, two types of the footbridge are being developed in parallel. Both footbridges are composed as the structures with a lower deck, truss main girders and bracings; the first structure (short footbridge) with a small self-weight may have the span up to 18 m; the second structure (long footbridge) with a normal self-weight may have the span up to 36 m. The paper is focused on the brief description of structural composition and parameters of the short footbridge, as well as structural detailing of the joints of main load-carrying parts. The configuration of the whole structure and individual structural details have been designed with respect to the static, dynamic and fatigue affects, which have been experimentally verified using loading tests of the footbridge prototype with the span of 18 m and fatigue tests of significant structural details.

Abstract: It is ascertained that the indicators weight system by the Analytic Hierarchy Process and constructed the model of success-degree evaluation method to execute the comprehensive evaluation for bridge preservation and replacement project based on the existing indicators system of bridge strengthening project with the purpose of success-degree in program evaluation. The success-degree classification of the bridge preservation and replacement project improves the system of post-evaluation for bridge preservation and replacement project through division of great success, success, partial success, most failure and failure. It indicates that the evaluation model is simple to assess and conform to the reality.

Abstract: Structural damage identification is the core of Structural health monitoring system. The paper points out existing damage identification methods and analysis the application status and disadvantages of various methods. The research hotspots are summarized on considering the statistical identification method under uncertainty and the environmental impact of damage identification methods. Aiming at the characters of bridge engineering, the paper points out that a four-in-one multi-system damage identification method is the develop direction for bridge structural damage identification, which is established based on construction, load testing, health monitoring and manual inspection.

Abstract: In recent years, we've paid more and more attention to the quality of bridges .So the detection of bridge structure is becoming more and more popular . In this paper we use a conventional continuous beam bridge as an example for the bridge detection method to do a simple narrative .This bridge is a newly completed one from ARongqi to BoKetu in the Inner Mongolia Autonomous Region .It is a continuous beam bridge goes across a provincial highway .We carried out this static and dynamic load test on this bridge, in order to get the information to guide the acceptance of the bridge. In this test we use a large number of professional softwares and equipments. And test this bridge in two different experimental methods to get the basic data acquisition of it as well as the bearing capacity .By analyzing these data to decide the construction quality.

Abstract: As we all know that the bridge may appear different diseases after years of operation. The static and dynamic tests are taken to test the actual working condition and the bearing capacity of the bridge. This article describes the principles and methods of the brdige test. We will analyze the tests, the data and information of bridge so that we can accumulate the mechanical characteristics of this bridge.

Abstract: The finite element model modified technique based on optimization principle is benefit for the model updating of the large bridge structures. By the ambient vibration test information provided by health monitoring system of huanghe bridge II in baotou , this article adopted corrected parameter based on structural eigenvalue sensitivity analysis to update the bridge dynamic model.The fundamental vibrational frequency of updated finite element model is more closer to the measured result under ambient excitation, which indicates that the optimization algorithm provided by large-scale general software can carry out the model updating effectively.

Abstract: To study validity of power spectrum density peak method which be used to identified modal parameter of concrete bridge under ambient excitation, number simulation of one Pre-stressed concrete bridge is carried out.3D model of the bridge is established by FEM software , FEM analysis and time-history analysis of 3D model of PC continuous beam bridge are carried out.During the simulation,practical factors such as acceleration measuring and white noise are taken into account. In the only case of the output signal modal parameter of bridge can be identified. Six-order modal parameters of the structure are identified by the number simulation which the average error is less than 5%. It is revealed that power spectrum density peak method is suitable for bridges monitoring and diagnosis, with important practical engineering application value.

Abstract: A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle. As critical transportation junction in the transportation network, bridge controls the traffic capacity of the transportation network. In the past decade, collapse of highway bridges caused by natural hazard and human error occur frequently. There are three main reason of collapse: 1) overloading; 2) construction deficiency; 3) imbalance of the system safety. In this paper, a collapsed bridge in Harbin is studied based on probability. A reliability analysis is conducted to investigate the system safety of the case bridge under combined effect of overloading and construction deficiency. Some suggestions for bridge quality control are proposed.

Abstract: Applying the combination of the natural excitation technique and the Eigen system realization algorithm, a finite element numerical simulation was performed for the dynamic behavior identification of a pre-stressed concrete continuous beam bridge under simulating wind load excitation. The results were validated comparatively using the combined algorithm of random decrement technique and Ibrahim time domain technique as well as the finite element modal analysis. The simulation results show that the wind load as the most common environmental excitation can be used effectively to identify the modal parameters of the concrete bridge.

Abstract: Due to the special geometry at the ends, skewed bridges are different from squared bridges. There are not lines about it in the code. Ansys is used to achieve the mechanical properties of the skewed bridges. Both static loading and moving loading were placed. It shows that the skewed bridges have unsymmetrical shear force at ends of each girder and the reaction at support with acute angle is larger than that at obtuse angle; with vertical loading, torsion exists in the girders except for flexure moment. Special consideration in bearing design is suggested.