how do architects calculate if a structure like a bridge is stable?
In: 2332
Safety factor vary by structure type, region, design methodology, etc… Most civil and structural engineers will set the limits at 4 or above for critical structures where loss of life is probable if it fails. This helps to account for conditions that go beyond the maximum loading (which is already generous), but more importantly, it allows for the non homogeneous nature of most of the materials that are used in daily construction. Steel is fairly uniform, but it’s exposure to the elements can and will degrade its section integrity over time. Reinforced concrete can have pocketed aggregate, voids, misplaced rebar, etc… Soil, even select material can vary greatly from load to load. Wood varies by direction of grain, wood type, treatment methods, and knot placement as well.
Additional factors such as historical data for wind, snow, earthquake magnitude, and other natural loads is still being developed and we don’t know the true risk factors. Items such as vehicle weights and maximum loading of trucks and rail cars has also increased greatly over the years. All of these things contribute to the need to apply generous overdesign to these types of structures.
Latest Answers