Final answer:
Single tee precast concrete is used in construction where thermal expansion and contraction need to be managed, like in bridges. Thermal expansion joints and the compatibility of expansion coefficients between concrete and steel reinforcement are crucial in preventing internal stress and damage.
Step-by-step explanation:
The use of single tee precast concrete is typically chosen for specific structural needs in construction. One of the key factors in deciding when to use this material is related to its capacity to handle thermal expansion and contraction. Structures like bridges and buildings are subject to various types of expansion and contraction due to several factors:
- Thermal expansion and contraction due to changes in temperature, which can affect the length and overall dimensions of structural components.
- Mechanical expansion and contraction due to loads moving on the structure, such as vehicles on a bridge, which can cause movement and stress.
- Load-induced expansion and contraction due to changes in the total load on a structure, affecting its integrity and stability.
To manage these stresses, thermal expansion joints are used in structures like bridges to allow for changes in length without causing damage or buckling. An example is the Auckland Harbour Bridge in New Zealand.
In the context of the materials used, the compatibility in coefficients of linear expansion between concrete and steel is crucial. Steel's coefficient is nearly identical to that of concrete, which is why steel is a common reinforcing material within concrete structures. This ensures that the structure can expand and contract without developing significant internal stress.
Therefore, single tee precast concrete can be appropriate for bridges with short spans where thermal stresses can be managed and for situations where minimal deflection is important.