Reinforced concrete is a famously durable construction material, but misconceptions and poor construction practices can lead to failure. Hee Yang Ng examines common design and construction situations that merit special attention to avoid structural failures with the use of reinforced concrete.



Reinforced concrete is a construction material widely used in many applications, including buildings, bridges, and other infrastructures. Due to its massive size and various redundancies, concrete structures are often considered solid, robust, and safe.

However, there have been instances of concrete structure failures and collapses, many due to erroneous assumptions or oversight by the designers in evaluating the design situation or poor construction practices. This article highlights several design and construction situations that designers and builders should pay special attention to in order to prevent failures.


Design of Silos

Silo structures are notoriously known to many as a structure requiring special attention, not because of the external loads, such as wind or seismic, but due to the storage load of the bulk solid. The unwary designer might unrealistically simplify and assume the load to be hydrostatic pressure caused by a fluid, even though the actual storage material might be solid granular material or particulate in nature.

The force exerted by particulate materials onto a silo container can be different. First, the designer must consider conditions during the filling up of the silo and discharging of the materials. There might be instances of eccentric loads (Figure 1) and higher loads (e.g., impact) caused by these processes. Next, there must be consideration of whether the presence of moisture, gas pressure, or other ancillary equipment imposes additional loads.

For example, some grains are known to absorb moisture and cause additional loads due to swelling of the grains. This example illustrates the importance of determining as accurately as possible the type of loadings exerted by different materials onto a structure, including loading magnitude, direction, and possible permutations in area.

Detailing a concrete silo with a single layer of reinforcement to deal with hoop tension only by assuming symmetric loadings would clearly be inadequate.