Final answer:
The two common footing problems with piers are inadequate footing and pier base not below the frost line. Proper sizing of footings and ensuring that the pier base extends below the frost line are crucial for structural stability. The correct option for these common problems is a. Inadequate footing and pier base not below the frost line.
Step-by-step explanation:
The two common footing problems with piers are a. Inadequate footing and pier base not below the frost line. Inadequate footing can lead to a situation where the foundation is not able to support the load of the structure, resulting in sinking or tilting. Additionally, if the pier base is not extended below the frost line, it can be subject to frost heaving, where frozen ground exerts upward pressure, causing the pier to move and destabilize the structure. Both these factors are critical in ensuring the stability and durability of a structure's foundation.
The correct option for the common footing problems with piers is a. Inadequate footing and pier base not below the frost line. It is important to properly size the footing to carry the intended loads and to ensure that the pier extends below the frost line to resist frost heaving.
To avoid these problems, engineers must consider soil conditions, local climate, and building load requirements during the planning and construction phases. Adequate design and construction practices will prevent costly repairs and safety hazards associated with inadequate footing and piers subject to frost movement.