Assignment Detail:- Part - Civil Works Design
You are required to undertake a civil construction design project as outlined below- Your Assessor will take the role of the client for the purposes of this assessment task-
Design Specifications
1- The Problem
You are a civil designer working for the state department of transportation- You have been assigned responsibility for the design of a truss bridge to carry a two-lane highway across the river valley shown below-
2- Design Objective
Satisfy all of the specifications listed below, while keeping the total cost of the project as low as possible-
3- Bridge Configuration1- The bridge may cross the valley at any elevation from the high water level to 24 meters above the high water level-2- If the elevation of the bridge is below 24 meters, excavation of the river banks will be required to achieve the correct highway elevation-3- To provide clearance for overhead power lines -shown above-, the highest point on the bridge may not exceed an elevation 32-5 meters above the high water level -8-5 meters above the top of the river banks--4- The bridge may consist of either standard -simple supports- or -arch supports-- If necessary, the bridge may also use one intermediate , located near the centre of the valley- If necessary, the bridge may also use cable , located 8 meters behind one or both abutments-5- Each main truss can have no more than 100 and no more than 200 -
6- The bridge will have a flat, reinforced deck- Two types of concrete are available:
1- Medium-strength concrete requires a deck thickness of 23 centimetres -0-23 metres--2- High-strength concrete requires a deck thickness of 15 centimetres -0-15 meter--
7- In either case, the deck will be supported by transverse spaced at 4 metre intervals- To accommodate these floor beams, your must have a row of joints spaced 4 meters apart at the level of the deck- These joints are created automatically when you begin a new design-8- The bridge deck will be 10 meters wide, such that it can accommodate two lanes of traffic-4- Member Properties
• Materials- Each member of the truss will be made of either carbon steel, high- strength low-alloy steel, or quenched and tempered steel-• - The members of the truss can be either solid bars or hollow tubes- Both types of cross-sections are square-• Member Size- Both cross-sections are available in a variety of standard sizes-
5- Loads
The bridge must be capable of safely carrying the following loads:
• Weight of the deck-• Weight of a 5-cm thick , which might be applied at some time in the future-• Weight of the steel floor beams and supplemental bracing members -assumed to be 12-0 applied at each deck-level joint--• Weight of the main trusses-• Either of two possible truck loadings:
• Weight of one standard H25 truck loading per lane, including appropriate allowance for the dynamic effects of the moving load- -Since the bridge carries two lanes of traffic, each main truss must safely carry one H25 vehicle, placed anywhere along the length of the deck--• Weight of a single 480 kN Permit Loading, including appropriate allowance for the dynamic effects of the moving load- -Since the Permit Loading is assumed to be cantered laterally, each main truss must safely carry one-half of the total vehicle weight, placed anywhere along the length of the deck--
6- Structural Safety
The bridge will comply with the structural provisions of the state specified standards, to include:
• Material densities
• Load combinations• Tensile strength of members• Compressive strength of members
7- Cost
The cost of the design will be calculated using the following cost factors:
• Material Cost:
• Carbon steel bars - $4-50 per kilogram• Carbon steel tubes - $6-30 per kilogram• High-strength steel bars - $5-00 per kilogram• High-strength steel tubes - $7-00 per kilogram• Quenched and tempered steel bars - $5-55 per kilogram• Quenched and tempered steel tubes - $7-75 per kilogram
• Steel Production-fabrication- Cost: $1000-00 per each steel pattern• Connection Cost: $500-00 per joint• Site Cost:
Required:
Part 1: -Design Analysis-
• Reinforced concrete deck -medium strength- - $5,150 per 4-meter panel• Reinforced concrete deck -high strength- - $5,300 per 4-meter panel• Excavation - $1-00 per cubic meter -See the Site Design Wizard for excavation volume-• Supports -abutments and pier- - Cost varies -See the Site Design Wizard for specific values-o $6,000 per anchorage
Refer to design model 1 document- Given the below forces:
Determine the horizontal and vertical components of reaction at the support-
Determine the forces in members 17, 19, 20, 16 and 21- State if the members are in tension or compression- Note that all angles are 45 degrees-
Part 2: -Estimation-
1- Make a detailed list of all constraints and requirements to the bridge design-
2- Three different materials available for the design of the bridge:• Carbon steel,• High-Strength Low-Alloy steel and• Quenched and Tempered Low-Alloy SteelDescribe the differences between these materials- Which material is the best choice for a given structural design????
3- One of the most important decisions in the bridge design is the selection of a cross- section type, solid bar or hollow tube, for each member in the structural model-At what locations should each type of cross section be used???? -Hint: you should consider the effect of the different cross-sections on member strength in both tension and compression--
4- A good engineer will try to find the best balance between the site cost -such site excavation, adding piers or cables- and the truss cost- Explain what is meant by this statement and provide some examples-
5- You are given two proposed designs that meet the design specifications- Estimate the total cost for each design and accordingly provide a recommendation on which model is more economical-6- For each design model, address its environmental impact on the surroundings such as the river channel-
7- Based on all your analysis -cost + environmental-, which is the optimum design????
8- Perform a risk assessment for the project taking into account all lifespan stages:• the existing conditions• the application of the design• maintainability of the works
Attachment:- Civil Works Design-rar
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