5.1. Beam to Beam (Secondary to Primary)

Types: Simple end-plate, cleat angle, seated connections.

There are three main types of connections used for connecting beams together: simple end-plate connections, cleat angle connections, and seated connections. Each type has its own unique design and application, but they all serve the purpose of connecting beams effectively in structural frameworks.

Imagine constructing a large wooden frame for a house. You would use different types of joints (like butted or corner joints) to connect wooden beams together, just like structural engineers use end-plates and cleat angles to join steel beams.

Bolted or welded, designed to transfer shear (and sometimes end reaction moments).

Beam-to-beam connections can be created using either bolts or welding methods. Bolted connections are often preferred for their speed and ease of assembly, allowing for adjustments on-site. Welded connections provide a strong joint with greater rigidity, ideal for permanent applications. Both methods are engineered specifically to manage forces and moments that act on the beams.

Think of bolted connections like using screws to assemble furniture—you can easily disassemble and reassemble if needed. Welding is more like permanently gluing parts together; it’s strong but difficult to change once set.

Beam to Column: Shear Connections - Simple Transfer shear only (common in simple construction). Moment Connections - Rigid Transfer shear and moment (for rigid frames).

In addition to connecting beams to each other, connections are also made between beams and columns. Shear connections are designed to carry shear forces without moment transfer, often used in simpler structures. In contrast, moment connections are designed to transfer both shear and moment, providing stability and rigidity to more complex, rigid frame structures.

Imagine a bookshelf (beam) resting against a wall (column). If you just lean it against the wall, it won't be very stable—this is like a shear connection. If you secure it tightly with brackets that keep it from tipping over, now it's like a moment connection, providing greater support and stability.

Stiffeners may be required for columns supporting heavy loads/moments.

When designing for connections that will support heavy loads or moments, additional structural elements known as stiffeners may be added to the columns. These stiffeners reinforce the connection, preventing failure due to excessive stress. The choice of whether to include stiffeners depends on the load conditions of the connection.

Think of a bridge. The beams that hold it up are strong, but the supporting columns need to be even stronger, especially in areas where heavy traffic will pass over. Adding extra support to the columns is like reinforcing a lightweight belt with extra fabric to ensure it can hold more weight without breaking.

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