Chapter 3: Structural infrastructure
Tags: Engineering, Infrastructure

All existing infrastructures include buildings, roads, dams, bridges, etc. However, this chapter only covers specific structures such as foundations, skyscrapers, schools, bridges, dams, levees, floodwalls and retaining walls.

Foundation is a vital part of a structure that support the building and ensures it does not experience tilting, sinking or other foundation related issues. Often steel or concrete piles, vertical structures embedded deep into the soil, are used where the soil is unstable or not capable of bearing the load. Another example is concrete footing that is built into the soil to increase the contact area of the structure and soil to help with the weight distribution by providing a larger area. Concrete slab is a flat surface used for floors and ceilings, and it is supported by other stronger structural elements.

Building foundations underwater is near to impossible which caused humans to seek alternative ways to tackle the problem. Caisson and cofferdams provide a practical solution to underwater construction. Caisson is an enclosed structure with pressurized air inside to prevent water from flowing in by seeping through the sand from the ground. Cofferdam is an enclosed wall, and later from which the inside water is pumped out.

Skyscrapers are becoming increasingly popular due to its ability to concentrate a large number of people in the same area, which allows us to reduce our human footprint on the planet. Foundation and structural design are complex and require qualification beyond a Bachelor’s degree.

School buildings require careful consideration beyond structural design as it is considered as in integral part of the neighborhood which has immense effects in the long-term. In order to meet the education demand, growing population needs to be predicted accurately to prevent built facilities from underutilization. It is a fact that rural areas are experiencing population decline, which leads to cost related losses in the long run.

Bridges not only serve a purpose but has the potential to become the landmark of the place. Bridges come in different shapes, each being more appropriate for certain situations based on the distance to be covered, medium (land or water), cost, ease of construction, site geology, users and aesthetics. Truss, arch, cable-stayed, suspension, beam and girder are the main types of bridges used.

Dams are built to provide household water supply and irrigation for agriculture, generate electricity, manage floods and provide recreational area.

Spillway is where the excess water is discharged into the stream without overflowing over the dam. There are 2 types of them: principal or service spillway that works under normal conditions and emergency or auxiliary where it works only during extreme situations.

There are a few different models of spillways such as morning glory shaped as a vortex exists to manage the water level in reservoir. Another type is weir which is a structure that allows the water flow over to the stream. They are both uncontrolled methods of spillways. However, controlled spillway is when the water flows through gates and these can be controlled depending on the level and flow of the water.

Next step would be to safely transport water downstream without it causing damage to the surrounding areas and the dam due to change in elevation and its high velocity. Chute is a channel like structure that allows the water gradually flow downstream and is usually built in open-channel spillways. Pipe or conduit is also used for the same purpose.

To prevent erosion and failure of the dam, construction of stilling basin with chute blocks or dragon teeth is required to achieve a hydraulic jump which dissipates the energy.

Flood gates and flood walls also function as flood prevention methods in more susceptible areas. However, multiple lines of defense (not relying on one particular structure) should be incorporated in flood prevention system. Levees are natural or artificial walls blocking water and used for the same purpose.

Retaining wall is a wall-like structure holding back the soil. Building a retaining wall and maintaining the area offsets the cost of purchasing a land by providing an additional space. The design heavily relies on calculations of lateral earth pressures, involving factor of safety against overturning, sliding, etc.