Design of Bridge Foundations using STAAD.Pro

Bridges are structures made of beams, columns, and trusses. They pass over obstacles and connect two disconnected ends. At the base of the bridge is the foundation that transfers loads from the superstructure to the ground. There are different types of bridges, each varying in the way they distribute load. The selection of a bridge depends on the load it has to handle, the location, resources, and the span needed. When designing bridge foundations, it is important for learners to understand the basics of bridges, their foundations, and the different types.

This week will cover

• Introduction to bridges
• Choosing the location, type, and material of a bridge
• Different types of bridges
• Introduction to the etymology of bridge components affecting foundations type
• Loads considered in the design of bridge foundations

Shallow foundations have a depth less than their width, and transfer loads close to the surface of the earth. These foundations are used when shallow layers of soil can support the loads, and are commonly used in the initial stages of developing highway bridges. It is important for learners to understand the different types of shallow foundations and the properties based on which they are selected.

This week will cover

• Types of foundations and their selection
• General description of foundations and their categories
• Brief description of the types of shallow foundations

Before structures like bridges are constructed at a site, the site is analyzed in terms of geographical, climatic, legal, and historical parameters. There are a series of calculations involved in this process. These site parameters help civil engineers determine whether the bridge can safely be constructed at the site. It is important for learners to understand the parameters considered for identifying a site, as well as the associated calculations.

This week will cover

• Site parameters and calculations involved in bridge design
• Introduction to material strength, survey data, geotechnical parameters, hydrology, liquefaction
• Shear failure

Abutments are found at the end of bridges and support the lateral and vertical loads acting on the superstructure. They safely balance these loads and transfer them to the ground. It is important to understand the design of abutments in shallow foundations in terms of their load bearing capacities.

This week will cover

• Design of shallow/open foundation in an abutment of a bridge
• Introduction to loadings on a bridge, stability checks involved, design parameters and their limits
• Detailing of reinforcement steel in the foundation

Piers are vertical members that provide intermediate support to the span of the bridge. They transfer vertical and lateral loads to the ground, and are commonly found in multi-span bridges that need more support between the abutments at the ends. It is important for learners to understand the design of piers in terms of their load bearing capacities.

This week will cover

• Design of shallow/open foundation for bridge piers
• Design parameters involved and checks for base slab design
• Detailing of reinforcement steel in the pier footing

Raft foundations have RC slabs extending over a large area, which is generally the footprint of the structure. Just like all bridge foundations, it transfers the weight and load of the structure to the ground. Raft foundations can be designed and analyzed using STAAD.Pro under varying loading conditions. When designing raft foundations, learners need to understand the theory behind it, as well as how loads can be applied and analysed using STAAD.Pro.

This week will cover

• Analysis of Raft foundation of box type vehicular underpass in STAAD.Pro and design/detailing as per limit state method
• Application of loads, analysis, and extraction of results from STAAD.Pro and designing of the base slab of a box type structure
• Detailing of reinforcement steel in the raft foundation

Deep foundations have a depth that is more than or equal to their width. They transfer loads farther away from the surface of the ground to competent layers of soil that can stabilize the structure. There are different types of deep foundations, each used for specific load bearing applications. It is important to understand the basics of deep foundations and the different types.

This week will cover

• Introduction to deep foundations
• Types of deep foundation, how to select the type, pros and cons of different types
• Factors affecting the sizes of foundations

Pile foundations are deep foundations that have many long columns placed into the ground. These foundations are generally composed of RC or steel, and include components like pile caps. When designing deep foundations, it is important for learners to understand the components involved to ensure they work together to effectively support the structure.

This week will cover

• Components of pile and well foundations
• Introduction to different kinds of pile systems, pile caps, and as per their end fixity
• Introduction to well steining, well curb, cutting edges, filling material of well foundations and their selection as per site

Before deep foundations are designed and inserted into the ground, the site is studied to understand the site parameters. This involves analysis and calculations that determine whether deep foundations can safely be inserted at the site. Engineers will then have to interpret this data. It is important for learners to understand the different site parameters considered during analysis, and how the resulting data is interpreted.

This week will cover

• Interpretation of data available from site studies
• Introduction to the scour calculations, geotechnical studies, Liquefactions, loading from the top (vertical as well as horizontal) for the deep foundations

After deep foundations are inserted into the ground, they are checked for stability. There are various stability checks that can be performed by engineers. It is important for learners to understand the different stability checks, and their importance in the safety of deep foundations.

This week will cover

• Different stability checks in the design of deep foundations and caps
• Stability checks involved in the pile and well foundations and their impact on the size or number of piles/diameter of well
• Characteristics of piles and the steps for design & installation

The design of pile foundations considers the length, size, depth, type, and number of piles needed to support the load of the whole superstructure. Engineers use the limit state method to consider the point of strength at which the structure experiences failure. It is important for learners to understand the limit state method, and how it is used in the design of buildings.

This week will cover

• Design of Pile foundation and its detailing by limit state method
• Introduction to the fixing of the length of piles, design as per limit state method and detailing
• Pile cap design

Well foundations are also deep foundations that extend below the surface level of water for bridges. They are used for the stability they offer during turbulent water conditions. As many bridges extend below the surface level of water, it is important for learners to understand the design of well foundations and their load bearing capacity.

This week will cover

• Design of well foundation and its detailing by limit state method
• Introduction to the design of well foundation as per limit state method and detailing
• RC details of well curb & cutting edge