Structural Steel-Connection Design-Summary by dRBI

Summary

This lesson on structural steel connection design focuses on bolted and welded connections, explaining the different types of steel connections and their applications. The lesson covers design processes for both non-preloaded and preloaded bolts, emphasizing the importance of shear strength, edge distance, and spacing. It also outlines the classification of connections based on various criteria, such as the type of internal forces and failure modes. The design of connections involves calculating ultimate and plastic resistance, with specific considerations for preloaded bolts. The session concludes by encouraging students to apply these principles effectively in their structural designs.

Takeaways

• 😀 Steel connections are used to join different members of a structural steel framework, primarily through bolts or welds.
• 😀 A bolt is a metal pin with a head at one end and a threaded shank at the other to receive a nut, commonly used for bolted joints.
• 😀 Welded connections join components by melting metals with or without filler material, creating a cohesive joint.
• 😀 Steel connections can be classified based on the connecting medium, internal forces, structural elements, and joining members.
• 😀 There are several failure modes for bolted connections, including single shear, double shear, bearing on plate, bolt shear tear-out, and tension failure of the plate.
• 😀 Non-preloaded bolts are typically sufficient for most connections, with minimal slip that doesn't affect the structure. They are cheaper and fall under bolt classes 4.6 and 5.8.
• 😀 Preloaded or pre-stressed bolts are tightened to a high tension, typically above yield strength, to provide additional strength but are more expensive, classified in bolt classes 8.8 and 10.9.
• 😀 The design of non-preloaded bolts involves five steps: calculating shear strength of bolts, determining minimum edge distance and spacing, calculating bearing resistance, and finding ultimate and plastic resistance.
• 😀 For pre-loaded bolts, the design process is simplified to four steps, where the design resistance is the smaller value between ultimate resistance and slip resistance force.
• 😀 Material properties and data are crucial for designing both non-preloaded and preloaded bolt connections, with a focus on strength and resistance calculations.

Q & A

What is the primary purpose of a steel connection in structural design?

Steel connections are structural elements used for joining different members of a structural steel framework.

What are the two main types of steel connections?

The two main types of steel connections are bolt connections and welded connections.

How does a bolt connection work?

A bolt connection uses a metal pin with a head formed at one end and a threaded shank at the other to receive a nut, joining the parts together.

What is welding, and how does it create a connection?

Welding is the process of locally melting metals with intense heating, using a filler metal or not, and allowing the molten materials to cool and form a coherent joint.

What are the four ways to classify a steel connection?

Steel connections can be classified based on the connecting medium, type of internal forces, type of structural elements, and the type of members joining.

What are the different failure modes of a bolted connection?

The failure modes of a bolted connection can include single shear, double shear, bearing on plate and bolt, shear tear out of plate, tension failure of plate, and block shear failure.

What is the difference between non-preloaded bolts and preloaded bolts?

Non-preloaded bolts are used in most standard connections and are cheaper, while preloaded bolts are tightened to a high tension above yield strength, making them more expensive.

What are the common bolt classes for non-preloaded bolts?

Non-preloaded bolts commonly come from bolt classes 4.6 and 5.8.

What are the common bolt classes for preloaded bolts?

Preloaded bolts are typically classified in bolt classes 8.8 and 10.9.

What are the steps involved in designing a connection for non-preloaded bolts?

The design steps for non-preloaded bolts include calculating shear strength of bolts, minimum edge distance, spacing requirements, bearing resistance for shear plane and bolt group, ultimate resistance, plastic resistance, and the final design resistance.

What is the process for designing a connection for preloaded bolts?

For preloaded bolts, the design involves four steps: calculating ultimate resistance, slip resistance, and selecting the smallest value between them to determine the design resistance.