Flush and Extended Multiple-Row Moment End-Plate Connections: Steel Design Guide Series

How to Apply Flush and Extended Multiple-Row Moment End-Plate Connections

Mastering the design of flush and extended multiple-row moment end-plate connections is crucial for structural engineers aiming to deliver efficient, robust, and code-compliant seismic and gravity load-resisting systems. This guide, derived from the AISC Steel Design Guide Series, empowers you to confidently implement these versatile connections, enhancing your design capabilities and professional reputation in the competitive field of structural engineering.

Before You Begin

Prerequisites:

• • Knowledge: A solid understanding of structural steel design principles, including LRFD and ASD methodologies, bolt shear and tension capacities, and basic mechanics of materials. Familiarity with AISC specifications is essential.
• • Tools/Resources: Access to the AISC Steel Design Guide Series, specifically the "Flush and Extended Multiple-Row Moment End-Plate Connections" manual, relevant AISC specifications (e.g., LRFD Specification for Structural Steel Buildings), structural analysis software, and standard engineering calculation tools.
• • Time Required: Approximately 2-4 hours, depending on the complexity of the connection being designed and the engineer's familiarity with the subject matter.

Step-by-Step Implementation

Step 1: Classify and Conceptualize the Connection

Begin by identifying the connection's role within the structural system. Determine if it's a flush or extended end-plate configuration, and consider the required moment capacity, rotation characteristics, and whether seismic loading or moment reversal is a factor. This initial classification informs subsequent design steps. A common mistake is to overlook the moment-rotation requirements, which can lead to unintended flexibility in rigid frames.

Step 2: Select an Appropriate Design Procedure

Refer to Chapter 2 of the guide to choose a suitable design procedure. The guide outlines yield-line theory-based approaches and bolt force prediction methods. Select the procedure that aligns with the connection type and the design philosophy (LRFD or ASD). Ensure you understand the underlying mechanics to correctly apply the selected procedure.

Step 3: Define Geometric Parameters and Material Properties

Establish the dimensions of the end plate, the beam section, and the bolt configuration (number of rows, bolt diameter, spacing). Accurately record the material properties for both the steel members and the bolts, including yield strength, ultimate strength, and bolt shear and tension capacities as per AISC specifications. Inaccurate geometric inputs are a frequent source of design errors.

Step 4: Calculate Bolt Forces and End-Plate Stresses

Apply the selected design procedure to determine the forces acting on the bolts (shear and tension) and the stresses within the end plate. This typically involves analyzing the moment applied and distributing it based on the bolt layout and plate stiffness. Understanding the interaction between bolt forces and plate deformation is critical for accurate analysis.

Step 5: Design the End Plate

Using the calculated forces and stresses, design the end plate's dimensions (thickness, width, length) and the bolt pattern to satisfy the limit states outlined in the guide. This includes checking for plate yielding, rupture, and block shear. For extended end plates, consider the cantilever action and potential for buckling. Incorrectly sizing the plate can lead to premature failure.

Step 6: Design the Bolted Assembly

Verify the adequacy of the bolts for the calculated shear and tension forces, considering bearing and shear-out conditions. Ensure proper bolt material grade and tightening procedures are specified. Overlooking bolt group effects or inadequate pre-tensioning can compromise connection integrity.

Step 7: Check Panel Zone and Stiffener Requirements (If Applicable)

If the connection is part of a beam-to-column joint, perform a panel zone check to ensure the column web can resist the shear forces transferred by the connection. If stiffeners are used, design them according to the guide's