Which type of construction is characterized by reinforced concrete, precast concrete, and protected steel frame?

The correct answer is that Type 1 construction is characterized by reinforced concrete, precast concrete, and protected steel frame. This type of construction is designed to provide high levels of fire resistance and integrity, using materials that can withstand significant exposure to heat without losing their structural integrity.

In Type 1 construction, the use of reinforced and precast concrete along with protected steel ensures that the building's elements do not combust and remain stable during a fire event, significantly enhancing fire safety. This type typically has a fire-resistance rating of at least two hours, which is an essential feature in high-rise buildings and structures that require greater protection against fire spread.

In contrast, the other types of construction have distinct characteristics. Type 2 construction is noncombustible but may not have the same level of fire resistance as Type 1. Type 3 construction includes both combustible and noncombustible materials, which makes it less fire-resistant compared to Type 1. Type 4 construction, often referred to as heavy timber, relies significantly on wooden structural elements, which are combustible and do not offer the fire-resistant properties of concrete and steel. This understanding highlights why Type 1 is the correct designation for the characteristics mentioned in the question.