Seismic Performance Assessment of Deteriorated Two-Span Reinforced Concrete Bridges

This paper presents a nonlinear analysis procedure for the seismic performance assessment of deteriorated reinforced concrete bridges using a modified damage index. A finite-element analysis program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), is used to analyze deteriorated two-span simply supported reinforced concrete bridges. The new nonlinear material models for deteriorated reinforced concrete behaviors were proposed, considering corrosion effects as shown in a reduction in reinforcement section and bond strength. A modified damage index aims to quantify the seismic performance level in deteriorated reinforced concrete bridges. Several parameters of two-span simply supported deteriorated reinforced concrete bridge have been studied to determine the seismic performance levels. The newly developed analytical method for assessing the seismic performance of deteriorated reinforced concrete bridges is verified by comparison with the experimental and analytical parameter results.

Lancashire County Council St Michaels and Carnforth Footbridges - United Kingdom

<p>Lancashire County Council (LCC) in UK are a forward thinking and innovative local authority with a significant number of bridges in their asset stock. They commissioned Jacobs to carry out a detailed options study for eight footbridges following concerns that were raised during principal inspections. The options report considered refurbishment and replacement options and the possibility of using new construction materials with the aim of maximizing durability and minimizing maintenance. The recommendations for all footbridges was replace them with Fibre Reinforced Polymer. LCC divided the eight bridges into packages of two according to their budget constraints and issued tender documents to contactors for the first two packages. The first package contractor has successfully delivered two replacement FRP Footbridges of 28m span over railway in Ormskirk. These are the longest simply supported FRP footbridges in the UK. The second tender package to be issued to tender was for St Michaels and Carnforth Footbridges at 37m and 31m spans. The Council wanted FRP Bow String Trusses for these bridges that crossed a River and a Canal respectively. Nothing like this type and scale of footbridges had ever been realized in the UK. This tender was won with an alternative proposal to replace these footbridges with an aluminium solution explaining to the client in doing so the risks and costs involved in designing and fabricating these structures in FRP would be significantly greater. These are the longest aluminum footbridges in the UK of this type.</p>

Splines in vibration analysis of non-homogeneous circular plates of quadratic thickness

Mathematical model to account for non-homogeneity of plate material is designed, keeping in mind all the physical aspects, and analyzed by applying quintic spline technique for the first time. This method has been applied earlier for other geometry of plates which shows its utility. Accuracy and versatility of the technique are established by comparing with the well-known existing results. Effect of quadratic thickness variation, an exponential variation of non-homogeneity in the radial direction, and variation in density; for the three different outer edge conditions namely clamped, simply supported and free have been computed using MATLAB for the first three modes of vibration. For all the three edge conditions, normalized transverse displacements for a specific plate have been presented which shows the shiftness of nodal radii with the effect of taperness.

An application of physics: simply supported bridges made of post-tensioned concrete and structural steel beams

Bridges represent an important application of physics capable of solving real transportation problems. Knowledge of convenience of different mechanical solutions when analyzing and designing bridge is needed. For these reasons, this work is focused on the study of convenience of using two types of bridges. Simply supported short-medium span bridges (30 m to 45 m) are usually excessively long when choosing reinforced concrete solutions and usually short for other types of structures such as cable-stayed or cantilever bridges. The suitability of simply supported bridges leads to the need of studying their cost benefit ratios. This work studies the cost benefit ratio for post-tensioned concrete beams and structural steel girders in simply supported straight bridges. Eight models built of type I sections were used in both cases to analyze the bridges using a software based on the stiffness method. Span of each bridge was set to 30 m, 35 m, 40 m, and 45 m. The convenience of each type of bridge was done comparing the total and the cost per linear meter of each solution (post-tensioned and structural steel). Comparison was done using material consumption, labor, and construction processes costs only. Also, allowable vertical displacement given by current bridge design standards was verified.

Analysis of Longitudinal Force of Beam and Rail of Continuously Welded Rails (CWR) on Railway Bridge

To study the longitudinal force of CWR on viaduct, a track-bridge-pier finite element model is established. Taking a multi-span simply supported beam with a maximum span of 32.7m of an elevated CWR as an example, the additional expansion and contraction forces, displacement between rail and beam and the force of pier are calculated, and whether the rail stress meets the requirements when setting constant resistance fasteners is checked. The results show that: (1) For the left and right lines, the maximum additional expansion forces of single strand rail are both 211.13kN, and the maximum relative displacements between beam and rail are both 6.572mm. (2) The maximum value of the additional expansion and contraction forces and the relative displacement between beam and rail of the same line occur at the same position. The left line is at ZFZ29 pier and the right line is at ZFS31 pier. (3) The maximum force of pier in this section is 500.80kN, and the pier numbers are ZFZ27 and ZFS29. (4) The rail stress is less than the allowable stress of 352MPa, and the rail strength meets the requirements.