Steel Structure.rtf

Objective of Civil Engineering Origin from the fata and have spend my childhood there have deep impact on my understanding and sleeting the course. The interest in structure and want to know the reason behind is from my origin. I was interested in the structural design of bridges made by the local over the rivers and the towers made at each house for protection. From that point I was interested in knowing the logic behind the towers and bridges and later became my compassion to choose the subjects. After taking the subject and my course of profession, the objective became clearer and the desire to understand the logic became widened in BUITEMS. From this course I want be able to understand the structural design, construction, surveys and the logic behind buildings and construction sites.

Steel Bridges Introduction

Steel is widely used all around the world for different construction purposes and among those bridges are one. The reason behind choosing steel for the bridges is that they have the strong sustainable future for maintaining that position. All over the world, steel has set that example for their strong future is that none of bridge hasn’t yet fall or damaged. There are also some example of steel based bridges in Pakistan which are yet standing among us.

Iconic steel bridge : Some of the impressive and visible bended steel bridges are well known all over the world that give a visible sense of their stiffness and long-lasting ability. These are based in different structure, design and construction and like Arch bridges. Chaotianmen bridge in China, New river Gorge Bridge in Spain, Bayonne Bridge in New York and

Ayub Bridge in Sukkur Pakistan are the famous Iconic steel bridge in world.

Ayub Arch Bridge : A famous Railway bridge in Pakistan, named after the Field Marshal Muhammad Ayub Khan, the President of Pakistan. The bridge is based on Arch design, bended, with one of the toughest materials known as Steel. The steel is still performing its core function well and in strong position. Not a single flaw yet showed by the iconic bridge.

Ayub Arch Bridge

Structure and Demographics : The bridge is situated between Rohri and Sukkur in Sindh province and the construction of the bridge was started in 1959. The project was completed in May 1962. The bridge is made with Iron and steel. Considering the dimensions of the bridge the total length is 806 feet, height is 247 feet and the track gauge is based on 1676 of train loadbearing rails. The bridge is situated over the Indus river. The designer of the bridge was David B Steinman and was only designed for Railway traffic. The structuring of was Arch bridge and Truss Arch bridge and both the deck and arch are made up of steel.

The Ayub bridge is constructed just aside Lansdowne Bridge to move the railway traffic to each bridge equally. The two half arches formed for supporting deck to cables and was one of the first bridge that hold

the railway desk with wire. The bridges are so close that for distance they look as one bridge.

Steel structure design Methods Basic design equation: F.O.S x LOAD < STRENGTH OF MATERIAL

As we study in the class there are many methods for steel structure design but the most common methods are LRFD and ASD.

1) LRFD: LRFD means load and resistance factor design. In LRFD method the factor of safety applied on both load (äct on the structure) and resistance (resistance of structure againts the applied load) of the material. Factor of safety means the ratio of ultimate strength of aa member ( column or beam ) to the working stress. The uncertainity of material strength and load also covered by the factor load or factor of safety. E.g. If we add F.O.S 1.2 to the applied load and the resistance, it will be 80% load = 20% resistance

2) ASD: ASD ( Allowable stress design) also known as Working Stress Design. In this method the factor load or factor of safety is applied only to resistance of the material. This design method is more safe and reserve as compared to the load and resistance factor design

(LRFD). The allowable stress design is calculated by

Load effects = material strength / F.O.S