Published online on May 2014.
Panagiotis Papanikolas, Aris Stathopoulos-Vlamis, Akis Panagis, Gerard Grillaud, Olivier Flamand
Abstract: The wind induced cable vibration was thoroughly investigated during design in order to provide suitable alleviation measures. The structural response analysis, as recorded by the monitoring system, concluded to the most appropriate technical improvement. Dampers installation improved the response of the stays, as indicated by commissioning tests and actual recordings.
International Journal of Bridge Engineering, Vol. 2, No. 1, 2014: pp. 1-16
Arman Shojaei, Hossein Tajmir Riahi, Siavash Haji Akbari Fini
Abstract: Incremental bridge launching is a widespread bridge construction method which may offer many advantages over conventional ones. In this technique, during phases of construction, internal forces of deck which may be more critical in comparison with those applied in service time, vary frequently. Therefore, an appropriate method shall be applied to reduce these forces and avoid eliminating the advantages of the method due to overdesigned structural members. For this purpose, using a nose-deck system is known as the standard method. In addition, mechanical and geometric characteristics of the launching nose are determinative based on launching stresses. Therefore, it is essential to carry out an optimal design procedure for the nose. In this paper, a new model based on matrix structural analysis is presented for the study of static behavior of bridge during launching stages. Also a simple method is introduced to scale all quantities in the procedure. Likewise, a simple model as a "semi-infinite beam" is introduced, which is useful for studying nose-deck interaction. Consequently, optimum design of the launching nose has been investigated through this model via a simple mathematical approach. It is shown that the accuracy of this model may not be satisfactory for initial stages of launching (or bridges with few numbers of spans). Therefore, some solutions are suggested to preserve the efficiency of the optimized nose for all stages of launching, in the view of optimum static performance of the bridge in service time.
International Journal of Bridge Engineering, Vol. 2, No. 1, 2014: pp. 17-42
Dimitrios Sophianopoulos, Panagiotis Tsopelas
Abstract: The dynamics of bridges with un-bonded post-tensioned piers under ground motion is considered. The actual bridge structure is modeled as a 3-DOF with 2-masses excited at the base by a simulated seismic motion. The effect of the parameters controlling the system dynamics is captured and important conclusions for structural design purposes are drawn.
International Journal of Bridge Engineering, Vol. 2, No. 1, 2014: pp. 43-51
Marwa M. Hassan, Angel Lence, Tyson Rupnow, Adam Zayor
Abstract: Biodeterioration on concrete surfaces of vertical elements of bridges represents a serious challenge to the US highway infrastructure especially in hot and humid states. The objective of this study is to present a qualitative analysis of successful methods and practices currently used to prevent and eliminate biofilm development on concrete surfaces. These baseline data are currently used by the Louisiana Department of Transportation and Development (LADOTD) to establish a maintenance protocol against biofilm in the state. To achieve this objective, a survey of current highway practices with respect to adopted cleaning and prevention methods was conducted. Further, a cost analysis between the most promising methods was conducted to determine which technique is the most suited for the transportation industry in terms of safety, performance, durability, and cost. Results of the qualitative analysis suggests that the main cause of biodeterioration of concrete surfaces is caused by micro-organisms' activity present at the surface. In addition, current practices used to prevent and clean biofilms growth are pressure washing, cleaning with biocides, and addition of photocatalytic nano titanium dioxide (TiO2) in the concrete mix or as a surface coating. Fromprevention and cleaning perspective, the use of photocatalytic nano TiO2 as a surface coating appears to be the most promising method in preventing microbial growth. However, TiO2 coatings may not perform successfully in areas in the shade or under the side of bridges.
International Journal of Bridge Engineering, Vol. 2, No. 1, 2014: pp. 53-72
Tassos P. Avraam, Theodore G. Konstantakopoulos
Abstract:For the analytical study of cables with dampers or movable anchorage finite series of sinusoidal form are usually used. This paper aims to determine the eigenfrequencies and shape functions of stay-cables with fixed or movable anchorages, in order to make the application of the modal superposition method easier and more accurate.
International Journal of Bridge Engineering, Vol. 2, No. 1, 2014: pp. 73-91