Bridge Structures

This paper presents a study about the spatial variability effects of ground motion and Soil-Pile-Structure Interaction (SPSI) on the dynamic response of a long bridge. The Spatially Varying Earthquake Ground Motion (SVEGM) is simulated by SIMQKE-II record generator. Target response spectrum and power spectral density function used in the simulation are determined depending on the January 17, 1994, Northridge earthquake. To evaluate the effect of SPSI, the soil surrounding the pile foundation is modelled by frequency- independent springs and dashpots in the horizontal and rotational directions. The effect of soil-pile mass is considered by lumped-mass soil-pile model. A new analytical model is proposed to study the effect of both SVEGM and SPSI on dynamic response of long bridges. The study reveals that the effect of both SVEGM and SPSI in the dynamic analysis and design should be considered simultaneously. A comparison between the results, based on the new suggested model and those given for other similar studies shows that the model could be applicable in calculation of dynamic response of long bridges. Considering the effect of soil-pile contributed mass along with the stiffness and damping is result in applying a model similar to a real soil-pile-structure system. It can simulate the real dynamic behavior of substructure more exactly.

Simple-span precast prestressed girders can achieve continuity, which in turn eliminates deck joints and protects the reinforcement from corrosion by preventing water leaks. The study presents a method to create continuity by casting a continuity diaphragm over supports and then post-tensioning the top end of the girders. The method exhibits all the advantages of a continuously post-tensioned technique. In the study, a bridge with three continuous spans was tested by using different truck loads at different positions. Stress on the girders and diaphragm were monitored by using the attached and impeded strain gages and a rosette. A three-dimensional finite element model was developed by using ANSYS and validated for the tested bridge. The FE model was used to analyze the transfer of stress between adjacent girders and spans. The results of FE model analysis indicated a strong correlation with the live load test data. Additionally, the results of the parametric study indicated that post-tensioning for continuity decreases the positive moments in the girders and leads to an increase in the transfer of stress between adjacent spans. It is expected that the results of the study will provide baseline data for these types of bridges.

This paper introduces a new approach for monitoring and system identification of suspension bridges. The methodology is based on the theoretical formulation of the dynamic response of a suspension bridge and its components. The vibration records are used to identify the boundary conditions and the unknown coefficients in the equations. The goal is to identify the forces in the main components of the bridge, rather than its modal properties. By proper placement of right-type of sensors, it is possible to identify the time-varying forces on the main suspension cables, hangers, towers, and the deck from the records.

A new metro bridge was constructed across the Golden Horn, Istanbul. The bridge consists of 2 approach viaducts, a cable-stayed bridge with a main span of 180 meters and a swing bridge. A metro station is situated in the centre of the main bridge. The deck of the cable-stayed bridge and the swing bridge are designed as steel structures. The bridge was equipped with a sophistic structural health monitoring solution, which will be delivered by VCE- Vienna Consulting Engineers. The paper describes the solution proposed by VCE. It covers the development and design of the instrumentation and the system for the monitoring of the behaviour, the performance and the condition of the structure. The monitoring concept consists of 3 subtasks:

Initial measurements and investigations after completion of the structure.

A special focus is on the data management part, which includes data archiving, data analysis and the presentation of the monitoring data to the operation personal and to the client. Apart from the control room devices the system will include a web-user interface, which allows a secure access to the monitoring data and results with mobile devices from anywhere and anytime.

During the past few decades, nondestructive damage evaluation (NDE) techniques are widely applied in industries, such as architecture, power plant equipment, and mechanical manufacture, etc. non-destructive damage detection techniques being applied to experimental data where it becomes a hotspot and challenging matter. Each of the NDE methods developed to date can be classified into different levels according to their performance and application. This paper will focus on the application of a Two Points -Condensation (TPC) technique. The TPC technique this method detect the damage based on vibration. The TPC technique reduces the structural system to two degrees of freedom system. The current stiffness matrices obtain from optimization the equation of motion of two degree of freedoms system using the measured test data. The current stiffness matrices compare with original (undamaged) stiffness matrices. The large percentage changes in matrices’ coefficients lead to the location of the damage. The improvement occurs in the reduction method, where the static condensation method replaced by the system equivalent reduction expansion process (SEREP) condensation method that provides a dependable result. The method allows fewer sensors than those required in the mentioned methods. The technique is applied to the experimental data of a steel truss bridge model structure after inducing the damage by removing an element from the specimen. The results show that the method detects the damage location area.