Developing a New Vibration Analysis Calculative Method for Esfahan Subway Train and Railways Design, Manufacturing and Construction
The simulated mass and spring evaluation for subway or railways construction and installation have wide applications in rail industries. This kind of design should be optimize all related parameters to reduce the amount of vibration in cities, residential areas, historical zones and other critical locations. Finite element method used too much to analyze such applications with an excellent accuracy but developing some simple, fast and user friendly evaluation always was required in subway industry. In addition, process parameter optimization required in railways to achieve optimal railways design with maximum safety, reliability and performance. The simple but useful simulated mass and spring evaluation system developed for Esfahan subway construction. This method discussed in this paper. Esfahan subway construction has a historical zone. Historical buildings should protect from harmful vibrations. Polyurethane layer used to reduce vibrations. This layer completely covered by concrete layers in all directions. It is worthy to know that, all the operation criteria like displacement and stress could be adapted with all vibration criteria like natural frequency, operation frequency and damping. Adaptation performed by changing in polyurethane layer thickness. The results showed that if 25-millimeter thickness polyurethane layer covered completely by two concrete layers with 12 millimeter thickness, the amounts of vibrations reduce considerably. In addition, it strongly recommended increasing the polyurethane layer up to 37 millimeter in historical zone to prevent potential harmful effects. The results confirmed by other commercial methods. The calculative method successfully performed. Furthermore, it is important to reduce maintenance costs in any potential design. The process parameter like rail ways dimension, rail ways material, cabins loading, cabins quality, cabins dimension and polyurethane layer thickness properly designed to keep the subway natural frequency around 18 Hz ( less than allowable 20 Hz). Numerical design results will protect all historical buildings, palaces paintings and old bridges in future subway operation times. In addition, some interesting patent and innovation in rail industry like Suspension mass tuned vibration reducer, short sleeper vibration-attenuation fastener and airtight track vibration noise reducing fastener discussed in this paper.
INSTALLATION OF HIGHLY EFFECTIVE VIBRATION MITIGATION MEASURES IN A RAILWAY TUNNEL IN COLOGNE, GERMANY
This article looks at the vibration mitigation measures which were implemented in a 970 m (3,132 ft) long section of a double-track railway tunnel in Cologne, in particular the individual elastic elements applied for vibration mitigation. It presents the results of structure-borne noise measurements, carried out both before and after the implementation of the measures. Finally, the effectiveness of the measures installed, i.e., their insertion loss, is compared with calculated values which were obtained using lumped-parameter models. The measurement results show a good consistency with the calculated values, and completely confirm the high expectations placed in the mitigation measures.
Using Fuzzy-Delphi technique to determine the concession period in BOT projects
BOT projects are affected by several risks and uncertainties. One of the most important issues in this type of contract is to determine the length of concession period considering these uncertainties. The previous studies have developed several models to determine the concession period. However, the uncertainties are not taking into account in most of the previous works. Moreover, none of the previous researches has the capability to aggregate the opinions of different experts being involved in a project regarding the values of the uncertain input parameters. In this research, a Fuzzy-Delphi technique is implemented to determine the length of concession period considering uncertainties. Using the proposed Fuzzy-Delphi technique, the values of different uncertain factors affecting a BOT project is determined considering opinions of a group of experts. The NPV value is calculated considering the resulted aggregated values of uncertain input parameters. Finally, the concession period is determined using fuzzy approach. A case study is conducted to evaluate the performance of the proposed methodology. It is shown that the concession period is determined more effectively using the proposed approach.