Steel braced frames and steel moment frames are two common structural systems used in the construction of buildings to resist lateral forces such as wind and seismic loads. While both systems are made of steel and provide stability to the structure, there are key differences in their design and performance.

Steel braced frames consist of vertical and diagonal steel braces that are connected to the beams and columns of the structure. These braces are designed to absorb and dissipate lateral forces, transferring them to the foundation of the building. The braces can be either concentric (axial) or eccentric (non-axial) depending on the structural requirements. Steel braced frames are typically used in low to mid-rise buildings where lateral forces are moderate.

On the other hand, steel moment frames rely on the bending capacity of the beams and columns to resist lateral forces. These frames are designed to provide rotational stiffness at the joints, allowing the structure to deform in a controlled manner during an earthquake or high wind event. Steel moment frames are commonly used in high-rise buildings where lateral forces are significant.

One of the main differences between steel braced frames and steel moment frames is their behavior under lateral loads. Steel braced frames rely on the axial strength of the braces to resist forces, while steel moment frames rely on the flexural strength of the beams and columns. This results in different levels of stiffness and ductility in the two systems.

In terms of construction and cost, steel braced frames are typically easier and faster to install compared to steel moment frames. The bracing elements can be prefabricated off-site and installed quickly, reducing construction time and labor costs. On the other hand, steel moment frames require more intricate connections and detailing at the joints, which can increase construction time and cost.

In conclusion, both steel braced frames and steel moment frames are effective structural systems for resisting lateral forces in buildings. The choice between the two systems depends on factors such as building height, occupancy, and lateral force requirements. Understanding the key differences between the two systems can help architects and engineers make informed decisions when designing buildings to ensure their safety and stability in various environmental conditions.