Quality Control of Pre-stressed Concrete Sleepers in Sudan Railways

Nowadays, railway transport plays a very important role in the transport system in a period of positive growth of commerce, economy and industry. In accordance with other modes of transport, railway is the most stable mode for transporting, safety, capability carrying, social and economic benefits. Sleepers have major roles in the complex railway system and distributed the load from rails when train goes through to the ballast. This study discussed pre-stressed concrete sleepers in Sudan railways and compare them with other varies of sleepers taken in consideration the service life, handling, weight of sleeper, damage, suitability for fastening and vibration resistance. On the other side explained the manufacturing stages that sleepers undergoes and the quality control accompanying them. A numerical static analysis for a pre-stressed concrete mono-block railway sleeper is carried out using finite element package named "ANSYS 15". Using SOLID65 solid element, the compressive strength of concrete is facilitated using plasticity algorithm while the concrete cracking in tension zone is accommodated by the nonlinear material model. Since the section of concrete sleeper is fully pre-stressed by nature, the smeared crack analogy is impracticable. Discrete reinforcement modeling with truss elements, LINK8, is then more suitable to utilize. Perfect bonding is presumed herein between concrete and pre-stressing wires. Thus, the results of the analysis that evaluate the effect of cables in deformed shape, strains, stress of pre-stressed concrete sleepers are compared to the solid concrete sleepers. Therefore, the insight into static behaviors will not only result in a safer and more reliable design method for railway infrastructure, but it can also translate and apply to other civil concrete structures.

Integration of advances in sustainable technologies for the development of the Sustainable Building Assessment Tool

The construction sector is a resource-driven and resource-dependent industry. A rising global interest to incorporate sustainability principles in the policy-making means a careful balancing of economic growth with sustainability. To achieve this end in the Indian building sector, a triple-bottom-line-based building assessment tool like GRIHA and IGBC was introduced for assessing building sustainability. However, to revitalize the ideas of Reduce, Replace, Reuse, Recycle and Renovate (the ‘5Rs’) into implementable solutions, the technological dimension is introduced to form a quadruple bottom line (QBL) approach, i.e., social, environmental, economic and technological (SEET), for achieving sustainable construction. This study aims to address the necessity to add a new dimension, viz. technological advances in the sustainability arena of the construction industry. The objective of the study is to include technological advances in building materials, construction processes and techniques and design philosophies in the developed SBAT framework. In this extended and upgraded SBAT 2.0, advances in sustainability (AS) criterion accounts for 11.5 per cent showing its significance in achieving building sustainability. The use of discrete reinforcement, additive manufacturing, 3D printing, design based on packing density and rheological properties of concrete, use of alkali-activated materials in the mix-design and performance-based design concepts that affect future sustainability are successfully brought into the fold of SBAT framework.

Coura and Valença Bridges on Minho Railway line – old structures, updated performance

<p>The pleasant Minho railway single lane line section from Caminha to Valença crosses the Minho river at Valença, through a very interesting and beautiful steel bridge. At Caminha it crosses the river Coura, by an also attractive steel bridge. Both are more than a century old and were refurbished and upgraded in a recent past and had before severe speed restrictions and load limitations:</p><ol><li> <p>Coura bridge: This 1879 iron bridge is a 3 span 164m lower deck continuous closed lattice girder, for a live load of only 4t/m without dynamic effects allowance. It was totally supported by a new continuous steel arch bridge, so both work together, combining in a very elegant construction.</p></li><li> <p>Valença bridge: This double-deck 1886 bridge is a steel 5 span 333m continuous lattice girder. Pathologies like excessive bending on the columns top sections, changing inappropriate bearing and a lock-up system for the braking action resulted in a demanding but discrete reinforcement.</p></li></ol>