Steel Design Guide: Hollow Structural Section Connections

How to Apply Steel Design Guide: Hollow Structural Section Connections

Mastering the design of Hollow Structural Section (HSS) connections is a critical skill for structural engineers seeking to optimize building aesthetics, material efficiency, and structural performance. This AISC Steel Design Guide provides essential, often complex, methodologies for HSS connections that extend beyond the foundational information in the main Steel Construction Manual. By thoroughly understanding and applying the principles within this guide, you can confidently design innovative and compliant HSS structures, enhancing your professional reputation and project success.

Before You Begin

Prerequisites:

• • Knowledge: A strong foundational understanding of the AISC Specification for Structural Steel Buildings (latest edition) and the AISC Steel Construction Manual is essential. Familiarity with general structural analysis, steel member design principles, and connection detailing is also required.
• • Tools/Resources: Access to the AISC Steel Design Guide 24: Hollow Structural Section Connections, the AISC Steel Construction Manual, and relevant structural design software. A calculator or computational tool for engineering calculations is necessary.
• • Time Required: Approximately 4-8 hours, depending on the complexity of the connection being designed and the user's familiarity with HSS connection design principles.

Step-by-Step Implementation

Step 1: Identify Connection Type and Geometry

Begin by precisely defining the HSS connection you are designing. This involves determining the type of HSS (round, square, rectangular), the main member (chord) and branch member configurations, and the orientation of the forces (e.g., axial, in-plane moment, out-of-plane moment). Accurately identifying the connection type is paramount, as different configurations are governed by distinct limit states and design procedures.

Step 2: Determine Applicable Limit States

Consult Chapter 6 and other relevant chapters of the Design Guide to identify all potential limit states that govern the performance of your specific HSS connection. These typically include chord wall plastification, punching shear, local yielding, sidewall failure, and weld or bolt failure. Understanding these limit states is crucial for ensuring the capacity of the connection meets or exceeds the applied loads.

Step 3: Extract Branch Loads and Chord Properties

From your structural analysis, obtain the design forces acting on the branch member(s) at the connection interface. Simultaneously, gather the geometric properties of the HSS chord, including its dimensions, wall thickness, and material grade. These inputs are fundamental for calculating the connection's nominal strength.

Step 4: Utilize Design Guide Tables and Specifications

Refer to the connection nominal strength tables provided in the Design Guide. These tables present simplified equations and capacities derived from the AISC Specification, often specific to various HSS connection configurations. Where tables are not directly applicable or for more complex scenarios, use the corresponding equations from Chapter K of the AISC Specification, referencing the Design Guide for clarity and specific application.

Step 5: Calculate Connection Nominal Strength

Using the extracted loads, member properties, and the relevant equations or tables from the Design Guide and AISC Specification, calculate the nominal strength for each governing limit state. Ensure you are using the correct resistance factors (LRFD) or safety factors (ASD) as per the Specification.

Step 6: Verify Capacity Against Demand

Compare the calculated nominal strength for each limit state against the factored or service loads (demand). The nominal strength must be greater than or equal to the demand for each limit state to ensure the connection is safe and adequate. If the capacity is insufficient, revise the HSS member sizes, connection geometry, or connection details.

Step 7: Detail Connections and Welds/Fasteners

Once the HSS members and connection geometry are verified, meticulously detail the connection. This includes specifying weld sizes, types, and lengths, or selecting appropriate bolts, their number, and arrangement. Ensure