Vehicle Bridge Interaction in High-Speed Rail Corridors

In this paper, our aim is to establish that Dynamic impact factor (DIF) is not only dependent on the span and type of the bridge but also dependent upon speed of the train and distance between axles of the train as well. Our current code i.e. Indian Railway Standards specify that DIF or Coefficient of Dynamic Augment (CDA) is dependent on span length and type of bridge but it is applicable for design speed up to 160 kmph. For any speed greater than that CDA shall need to be computed as per the dynamic analysis as per available international codes. As mentioned earlier that there is imminent need of high-speed rail network in India due to increase in economic activity, increase in travel choices, improvement in mobility, reduction in congestion and to boost productivity. Our objective of this project is to study dynamic response of a various types of bridges under high speed trains currently being used in India for high speed rail projects like RRTS (Delhi to Meerut and other corridors) and High speed rail project from Mumbai to Ahmedabad to accurately assess the DIF in bridges under the effect of different governing factors (vehicle speed, vehicle load, bridge superstructure type, etc). This study could be beneficial in upcoming projects of high-speed rail as it is our future need. This study is based on the current semi-high-speed rail network i.e. Delhi Meerut Rapid Rail Transit System (RRTS) being constructed and other corridors are to be implemented. Design speed of this project is 180 kmph hence existing IRS codal provision for DIF cannot be used, therefore, dynamic analysis is needed to establish the DIF. Dynamic analysis has been carried out with two types of boggie length i.e. 21.34m and 22.34m. In this project, we have started with the understanding of dynamic analysis by mentioning various codal provisions and parameters influencing the DIF. Subsequently, procedures for computation of dynamic analysis for given superstructure, loading, train type, span, etc have been explained including the modelling part. Last part of this study covers the dynamic analysis of various types of superstructure for given data

Assessment of the Soft-Tissue Seal at the Interface between the Base of the Fixed Denture Pontic and the Oral Mucosa

Fixed dentures (bridges) are often selected as a treatment option for a defective prosthesis. In this study, we assess the contact condition between the base of the pontic and oral mucosa, and examine the effect of prosthetic preparation and material biocompatibility. The molars were removed and replaced with experimental implants with a free-end type bridge superstructure after one week. In Experiment 1, we assessed different types of prosthetic pre-treatment: (1) the untreated control group (Con: mucosa recovering from the tooth extraction); (2) the laser irradiation group (Las: mucosa recovering after the damage caused by a CO2 laser); and (3) the tooth extraction group (Ext: mucosa recovering immediately after the teeth extraction). In Experiment 2, five materials (titanium, zirconia, porcelain, gold-platinum alloy, and self-curing resin) were placed at the base of the bridge pontic. Four weeks after the placement of the bridge, the mucosa adjacent to the pontic base was histologically analyzed. In Experiment 1, the Con and Las groups exhibited no formation of an epithelial sealing structure on the pontic base. In the Ext group, adherent epithelium was observed. In Experiment 2, the sealing properties at the pontic interface were superior for titanium and the zirconia compared with those made of porcelain or gold-platinum alloy. In the resin group, a clear delay in epithelial healing was observed.

Strengthening of Burri box Girder Bridge by using External post Tensioning Technology (Sudan)

Ageing, and increasing traffic loads, has become a major problem into today bridge industry. These bridges go deficiency in its Load Carrying Capacity from ageing, exhibited in excessive deformation which renders the bridge usage to an unacceptable level. These will either, impose traffic restriction, or upgrading the existing bridges to defy these adverse conditions. At Burri Bridge, after 33 years on operation, signs of ageing showed in the excessive deformation and the departure of the deformed shape of the super structure from the design profile, and travelling along the bridge was un-comfortable and difficult trip riding. The Objective was to explore the strengthening of the Burri Bridge by using external post tensioned tendons to mitigate the ageing effects and to elevate the capacity of the bridge. It was requisite to examine the bridge before the application of external tendons to insure the stresses in its past status will qualify it for repair. Hence, the present study contains the analysis of the Bridge superstructure in two stages. The first is done in its Past status, and the second when external tendons are added to boost its capacity and defy the effect of past load level, and a new standard load tested. The model was analyzed using Midas Civil software. The study includes the design of the anchor beams where the fresh external tendons are terminated. The study proved that, the capacity of the Bridge is increased by 4.6 %, and this is interpreted in the increase of the Ultimate Flexural Strength and the decrease of the deformation after adding these external tendons. Some of the Techniques implemented are presented.

Rehabilitation of Blue Nile Steel Bridge Superstructure: Fatigue Assessment

The Blue Nile Steel Bridge over the Blue Nile River in Khartoum, Sudan, has been in service for 112 years. A riveted steel through-truss of Pettit Configuration with seven equal fixed spans of 65.53 m and a rolling lift span. The bridge currently accommodates approximately 61,000 vehicles per day along with insignificant pedestrian and railway traffic. Over the years from 1960 to 2014 several assessment studies were carried out by numerous parties have revealed that under cyclic loading of a long period time and effects of natural and man-made disasters, bridge deck was damaged severely and needed to be repaired and strengthened. A rehabilitation program was planned to extend the design life of the bridge for a more 50 years, which was carried out in period (2017 - 2018).This paper presents as a case study including a literature review on fatigue assessment of stringers on railway track. The rationale for selecting the rehabilitation strategy for the bridge is described, highlighting the challenging design aspects related to fatigue assessment, clarifying the methodology in which main members were identified for strengthening, using Midas Civil 2006 v7.01 and Midas FEA 2016 v1.1software to analyze the fatigue in the critical members by generating a model using Finite Element Method and estimating remaining fatigue life by adopting the classical approach (Stress-life method), the total damage accumulation was found greater than 1. Thus, it can be concluded that the stringers have no remaining fatigue life. Strengthening the stringers is considered the most favorable solution.

The use of a new slab track system in the renovation of the Vierendeel railway bridges in Mechelen

<p>The existing ballastless track with wooden sleepers on the Vierendeel bridges in Mechelen will be replaced by a new slab track system with continuously welded rails across the bridge. Additionally, the rails will be positioned eccentrically on the stringers due to track optimization. This paper describes the design and implementation of this new modular track system that consists of prefabricated fully welded steel frames that are bolted onto the existing superstructure. During the design stage, focus was on the required load transfer via the steel frame to the bridge superstructure, on the large difference in steel characteristics between the old and new material and on the position of joints and fastenings. Lateral and longitudinal stiffness of the track was tested on a prototype and the final solution was already installed and successfully implemented on one bridge. In addition, field tests in relation to rail-bridge interaction have started.</p>

Darlington Upgrade Project – Bridge design for manufacture and assembly

<p>The Darlington Upgrade Project (DUP) consists of the upgrade of approximately 3.3 kilometres of the existing Main South Road forming part of the Adelaide North-South Transport Corridor.</p><p>This paper focusses on the design of the project’s three composite steel box girder bridges and challenges employing the Design for Manufacture and Assembly (DfMA) principles on the bridge superstructures which were constructed on temporary towers in an assembly yard approximately 500 metres from the final bridge position and transported using the Self-Propelled Modular Transporter (SPMT) technology. SPMTs, a first in Australia for bridge application, allows pre- fabrication of the bridge superstructure improving safety for both construction crews and motorists.</p><p>Evaluation of stresses imposed on the superstructure obtained from the real time monitoring instrumentation during installation is also presented.</p>

Automated design of the railway bridge structure

This paper presents the design and calculations of bridge structures using modern computer technology. They provide the special capabilities necessary for the design of bridges, for example, the construction of influence lines for calculating moving loads, for calculating nodal interfaces, for checking local stability, for calculating the thermal stress state of supports, etc. The main purpose of the survey of the bridge structures was to obtain the initial data in accordance with GOST-v and SNiP-v for calculating the carrying capacity of the bridge superstructure, assessing the technical condition and developing recommendations for its further operation.