Building with Vision: The Basics of Concrete Construction
In the realm of construction, grasping the fundamentals of concrete construction is a crucial skill that builds common sense. As you delve into a set of drawings, envision the construction process unfolding in your mind, brick by brick. Gravity dictates that the first element constructed rests at the base, forming the foundation of the structure.
While excavation estimation may not be our central focus here, comprehending excavation procedures is essential for visualizing the entire construction process. The foundation marks the initial point of contact between the structure and the ground. Earth exhibits diverse densities – from sand and dense soil to rock and water – often coexisting within the same building area. To comprehend the soil conditions of an area, an engineering firm must conduct a Geotechnical report. This report illuminates the soil composition, water levels, and soil capacity, offering insights to design engineers for crafting suitable foundations.
Every building’s foundation rests on the ground through concrete elements known as footings. The dimensions of footings vary depending on the soil’s load-bearing capacity. Consider a structure with two column footings; these footings bear the entire weight of the building, transmitting it to the ground. Consequently, the ground must withstand the building’s weight.
Structural engineers calculate the anticipated loads a building will bear. This calculation goes beyond mere concrete and steel weight; it also factors in the building’s purpose. A residential space accommodating one or two individuals per 400 square feet differs significantly from a stadium designed to accommodate two individuals per 2 square feet. The calculation considers additional elements like snow and wind loads.
In the context of this discussion, we are primarily concerned with the maximum downward weight that the soil can support. Let’s imagine a Geotechnical report indicating a soil capacity of 1000 lbs per square foot. Suppose the design engineer determines that the column footings should measure 10’x10′. This implies that the column footing can bear an area of 100 square feet (bottom area of the column footing) multiplied by 1000 lbs per square foot (soil capacity) – yielding 100,000 lbs.
Should we exceed the load limit of 100,000 lbs, the footing may sink into the soil. Such an event could lead to cracks in the building, potentially causing significant structural issues. When the soil capacity is higher, say 2000 lbs per square foot, a 100,000 lbs load would require a smaller footing size: 100,000 lbs divided by 2000 lbs per square foot – resulting in an approximate size of 50 square feet, or about 7’1″x7’1″.
Visualizing this scenario is akin to walking on snow – you require snowshoes to distribute your weight because snow, being softer, has a lower load-bearing capacity compared to solid ground. Hence, when confronted with structural drawings featuring extensive column footing dimensions, it’s indicative of lower ground capacity, thus requiring larger surface areas on the concrete elements in contact with the ground.
Understanding foundation concrete elements is a cornerstone skill in construction, enabling professionals to make informed decisions that ensure structural stability and longevity.
