Steel Design Guide: Extended End-Plate Moment Connections - Seismic and Wind Applications

How to Apply Steel Design Guide: Extended End-Plate Moment Connections - Seismic and Wind Applications

Mastering the design of extended end-plate moment connections is crucial for engineers tasked with creating robust and resilient steel structures, particularly those subjected to significant seismic or wind forces. This AISC Design Guide provides a comprehensive framework for these critical connections, ensuring their reliability and performance under extreme loading conditions. By following this guide, you can confidently design connections that meet stringent code requirements and contribute to the overall safety and longevity of your projects.

Before You Begin

Prerequisites:

• • Knowledge: Solid understanding of structural analysis principles, steel design codes (e.g., AISC 360), and fundamental concepts of seismic and wind engineering. Familiarity with moment-resisting frames and connection behavior is essential.
• • Tools/Resources: Access to the AISC Steel Design Guide: Extended End-Plate Moment Connections - Seismic and Wind Applications, the AISC Steel Construction Manual, relevant design software (for analysis and member checks), and standard engineering calculation tools.
• • Time Required: Allow 4-8 hours for initial comprehension and detailed design of a single connection, depending on complexity and familiarity with the document.

Step-by-Step Implementation

Step 1: Define Connection Requirements and Load Cases

Clearly establish the design moment, shear forces, and axial loads the connection must resist for both seismic and wind conditions. Understand the intended application (e.g., beam-to-column, beam-to-girder) and the required performance level (e.g., fully restrained, limited ductility). This foundational step dictates all subsequent design decisions and ensures you are addressing the correct design criteria from the outset.

Step 2: Select an Appropriate Extended End-Plate Configuration

Based on the anticipated forces and geometric constraints, choose from the available configurations presented in the guide (e.g., four-bolt unstiffened, four-bolt stiffened, eight-bolt stiffened). The guide details the suitability of these configurations for seismic applications. Misselecting a configuration can lead to inefficient design or failure to meet performance objectives.

Step 3: Determine End-Plate Dimensions and Bolt Layout

Calculate the required end-plate thickness, width, and height to accommodate the selected bolt pattern and adequately resist the applied forces. The guide provides methodologies for determining these dimensions, often involving yield line theory or equivalent models, and considerations for bolt placement to optimize force distribution. Ensure sufficient edge distances and spacing are maintained as per AISC requirements.

Step 4: Design and Verify Bolt Group Capacity

Analyze the bolt group to ensure it can withstand the combined tensile and shear forces derived from the connection design moment and shear. This involves checking individual bolt capacities in tension and shear, considering prying action, and verifying the overall strength of the bolt group against the applied loads. The guide outlines specific bolt force models and limit state checks.

Step 5: Design and Verify End-Plate Strength

Assess the capacity of the end plate itself to resist yielding, rupture, and block shear in tension and shear. This check is critical as the end plate acts as a critical load transfer element. Use the design procedures outlined in the guide, which often incorporate yield line theory to establish the plate's ultimate strength under various failure modes.

Step 6: Design and Verify Welds

Determine the required weld size and type for connecting the end plate to the beam web and flange. Ensure that the welds have sufficient strength to transfer the forces from the end plate to the beam section without exceeding their capacity. Refer to AISC 360 for weld design provisions and consider the potential for lamellar tearing in thicker plates.

Step 7: Check Column/Supporting Member Capacity

Verify that the supporting member (e.g., column) has adequate capacity to resist the forces transferred from