Accelerating Steel Frame Design Verification: A Step-by-Step Guide for Eurocode Compliance

Steel frames are fundamental to modern engineering. Verifying that these frames can withstand all expected loads and stresses is complex and critical; a single missed calculation or unchecked joint could compromise the entire structure.

The Eurocode standards set the rules for engineering across Europe, defining precise requirements for every bolt, weld, and load path. These standards are thorough but demanding, requiring engineers to analyze numerous load combinations and check each joint and member meticulously. 

This article breaks down the verification process, highlights key challenges in steel frame compliance, and presents a streamlined solution to simplify structural integrity verification.

Key Challenges in Steel Frame Verification

When working with industrial or civil structures, we deal with layers of complexity in the frame design and the environment it’s built to withstand. Think about it: these frames have to manage their weight and variable loads like wind, snow, and equipment that can fluctuate significantly. Each of these forces puts pressure on different parts of the frame in unique ways, and even small changes in conditions can affect the structure’s integrity.

One of the biggest challenges here is the sheer intricacy of these structures. Industrial steel frames, for example, consist of hundreds or even thousands of individual members, each connected by welds, bolts, or both. The layout of these members isn’t arbitrary — they’re carefully arranged to distribute loads and maintain stability. However, with so many interconnected components, creating a domino effect only takes one weak point, compromising the whole structure. Every joint, connection, and load-bearing element must be meticulously verified for strength and compliance.

Traditionally, this verification process has been done manually. But in manual verification, accuracy and efficiency become real hurdles. Checking every load path, calculating every load combination, and inspecting each joint one by one isn’t just time-consuming — it’s prone to human error, especially when dealing with complex models and stringent Eurocode requirements. We’re talking about engineers spending hours, sometimes days, on a single verification process, often going back and forth to ensure nothing has been missed.

The challenge is clear: engineers need a way to handle the complexity without compromising precision. As projects grow in scale and timelines tighten, the demand for streamlined, automated verification processes is more pressing than ever.

Step-by-Step Verification Process with SDC Verifier

Step 1: Model Setup and Load Application in Steel Frame Verification

Setting up an accurate FEA (Finite Element Analysis) model is the foundation of any steel frame verification process. Engineers define the frame geometry, material properties, and load conditions in this stage to reflect real-world scenarios as closely as possible. With SDC Verifier, setting up the FEA model involves a few essential steps that ensure each structural element and its interactions are correctly accounted for in the analysis.

In FEA model preparation, we start by defining the geometry — each beam, column, joint, and support is modeled to match the design specifications. Material properties, like yield strength and elasticity, are assigned to these members. This is crucial because each element in a steel frame responds differently under stress, and accurate material properties allow the model to predict those responses precisely.

Once the frame is set up, we apply loads to the model. Here’s where things get detailed: industrial and civil steel structures encounter various loads, from permanent dead loads (like the structure’s weight and equipment) to variable live loads (like wind, snow, and seismic forces). With SDC Verifier, engineers can apply each load type individually and in combinations, according to Eurocode standards, ensuring that the model accurately reflects how load cases impact the structure.

After defining the frame geometry and applying loads, engineers establish the necessary constraints. Constraints are critical because they determine how the frame is fixed or supported in the model, directly affecting how loads are distributed and how the structure behaves under stress. The above image shows constraint points applied across various support areas, providing a visual representation of how the structure is anchored in the analysis.

By the end of this setup, the FEA model serves as a virtual replica of the real-world steel frame, capturing both the expected and extreme conditions it will face. With the model and loads in place, we’re ready to move on to load combinations and structural member recognition, taking us one step closer to comprehensive verification.

Step 2: Load Combination Creation in Steel Frame Verification

Each steel structure faces multiple types of loads — dead loads, live loads, wind, snow, and sometimes seismic forces. However, the objective complexity lies in understanding how these loads interact, especially under varying conditions. 

In traditional setups, manually calculating load combinations can be exhaustive. Engineers have to consider each load’s impact on every structural member, adjusting for partial safety factors, dynamic factors, and any code-specific requirements. Missing a single factor or misjudging a load’s influence could lead to inaccurate results. SDC Verifier addresses this by allowing engineers to easily define, group, and apply these combinations, automating the adjustments for safety and dynamic factors specified by Eurocode.

Through SDC Verifier, you can choose between manually entering load combinations or using predefined combinations based on industry standards. For Eurocode-compliant designs, each load combination is carefully crafted with the prescribed partial safety factors and dynamic considerations, significantly reducing the risk of human error. It also means engineers can save hours of manual calculation time, focusing instead on interpreting results and making critical design decisions.

By the end of the load combination stage, we have a comprehensive set of load cases that accurately reflect how various forces impact the structure under real-world conditions. 

Once load applications and constraints are set, analyzing stress distribution across the steel frame structure is a critical step. SDC Verifier calculates stress levels to ensure that each member can withstand the applied loads without failure, identifying areas of high stress that may require design adjustments.

Stress distribution across the steel frame structure, highlighting areas with high stress concentrations. The color gradient provides a visual representation of equivalent absolute stress values in Pascals (Pa), allowing engineers to quickly identify critical stress points.

In this analysis, areas highlighted in warmer colors (closer to red) indicate higher stress concentrations, which are crucial to monitor for potential structural vulnerabilities. By identifying these areas, engineers can make informed decisions on reinforcing or adjusting design parameters to enhance structural integrity.

Step 3: Automated Recognition Tools in Steel Frame Verification

One of the most challenging aspects of steel frame verification is identifying and categorizing every member, joint, and weld within a complex structure. Each component — whether it’s a load-bearing beam, a connecting joint, or a reinforcing weld — has a unique role in the structure’s integrity.

Beam Member Finder identifying members in the Y and Z directions, critical for calculating accurate buckling lengths and ensuring structural stability.

SDC Verifier’s member recognition tool automatically detects and categorizes beams, columns, and braces within the model, tagging each with specific parameters, such as length, cross-section, and orientation. 

Beam Member Finder interface showing node identification, member lengths (Y and Z directions), torsional settings, and joint configurations for comprehensive analysis.

The software’s joint recognition tool goes a step further, identifying all connections within the frame. Joints are often high-stress points in any structure, especially under dynamic loads like wind or seismic forces. SDC Verifier automatically classifies each joint type (fixed, pinned, or partially restrained) and calculates the appropriate buckling lengths for accurate verification. 

The weld recognition tool identifies welded areas and characterizes structures that rely on welds based on thickness and type. This tool helps engineers ensure that each weld meets specific strength requirements under Eurocode standards. 

This automation allows engineers to focus on the bigger picture — analyzing results and refining designs — without getting bogged down in tedious, repetitive tasks.

Step 4: Eurocode Compliance Checks in Steel Frame Verification

When it comes to steel frame verification, ensuring Eurocode compliance is non-negotiable. Eurocode standards set the benchmark for safety and reliability across structural elements, demanding precise checks for everything from member buckling to joint stability and weld integrity. 

Eurocode 3 Member Checks (EN 1993-1-1, 2005)

The Eurocode 3 standard, specifically EN 1993-1-1 (2005), outlines the core guidelines for verifying steel structural members. This standard focuses on ensuring that steel beams, channels, tees, tubes, and bars are designed and verified to withstand their respective loading conditions without compromising safety. Particularly when assessing ultimate limit states, which define the structural capacity under peak loads.

SDC Verifier implements Chapter 6 of Eurocode 3, which addresses ultimate limit states for a range of cross-section shapes, including I-beams, channels, tees, and rectangular and circular tubes. By following the steps below, engineers can configure the Eurocode 3 standard for thorough member checks:

1. Adding the Standard in SDC Verifier

   From the main ribbon, select Standards – Main – Eurocode3 – Eurocode3 Members (EN 1993-1-1, 2005). Here, you can set specific standard parameters tailored to the project’s needs.

2. Setting Custom Parameters:

   • Partial Safety Factors (γm): These factors address different resistances:
     • γm0: Cross-section resistance (default = 1.00)
     • γm1: Member instability resistance (default = 1.00)
     • γm2: Tension resistance (default = 1.25)
   • Lateral Torsional Buckling Factors:
     • For rolled or welded sections, set λLT,0 (recommended maximum of 0.4) and β (recommended minimum of 0.75) as specified in the National Annex.

3. Cross-Section Classification:

   • Each member’s cross-section is classified into Class 1-3, defining its resistance to buckling. Fillets should be defined in the model, as missing fillets can lead to conservative, less accurate results. For accurate shear and buckling checks, modify the cross-section shape and moment of inertia accordingly.

4. Slenderness and Buckling Parameters:

   • SDC Verifier automatically calculates member slenderness based on length and end conditions, using factors from the National Annex. For torsional buckling, effective lengths in the y and z directions are calculated to determine the slenderness ratio and resistance factor.

5. Shear Area and Resistance Calculations:

   • Shear areas are calculated based on member type, whether it’s a rolled I-beam, channel, or hollow section. When shear force exceeds half the plastic shear resistance, SDC Verifier applies reduced yield stress to ensure conservative shear resistance, per Eurocode requirements.

Eurocode 3 Bolt Checks (EN 1993-1-8, 2005)

The Eurocode 3 bolt checks, outlined in EN 1993-1-8 (2005), provide specific guidelines for verifying bolts under various loading and connection conditions.

1. Configuring Bolts in SDC Verifier:

   • Access Standards – Main – Eurocode3 – Eurocode3 Bolts (EN 1993-1-8, 2005) from the ribbon, then customize settings to match bolt types, positions, and load directions as required by the design.

2. Key Bolt Parameters:

   • Bolt Position and Load Direction: SDC Verifier recognizes whether bolts are in end or inner positions, critical for determining shear resistance.
   • Threaded vs. Unthreaded Shear Planes: SDC Verifier allows engineers to set whether shear passes through the threaded or unthreaded portion, impacting shear resistance.
   • Countersinking, Friction Class, and Edge Distances: These factors are essential for calculating slip resistance, bearing resistance, and edge distance compliance, as detailed in Eurocode’s bolt tables (e.g., Table 3.4 and Figure 3.1).

3. Slip Resistance and Preloading:

   • For preloaded bolts, the Class of Friction Surface determines the slip factor, which SDC Verifier uses to calculate slip resistance at both serviceability and ultimate limit states.

4. Resistance Calculations and Safety Factors:

   • With partial factors (e.g., γM2 for bolts), SDC Verifier automatically applies the relevant safety margins in each calculation, ensuring that all bolts meet the required resistance levels under Eurocode.

Eurocode 3 Weld Strength Checks (EN 1993-1-8, 2005)

EN 1993-1-8 (2005) provides guidelines for evaluating the weld strength and stability of joints under tension, compression, and shear forces.

1. Configuring Weld Standards:

   • In SDC Verifier, navigate to Standards – Main – Eurocode3 – Eurocode3 Welds (EN 1993-1-8, 2005). Here, engineers can set parameters like material type and Beta_w correlation factors from Table 4.1, section 4.5.3.2, based on weld material.

1. Weld Stress Calculations:

   • SDC Verifier calculates weld stresses at critical points, including the start and end of each weld. This approach provides a complete stress profile along the weld length and ensures the calculated stresses match the von Mises stress distribution, adhering to Eurocode’s guidelines.

2. Utilization Factor and Resistance Checks:

   • For each weld, SDC Verifier calculates a utilization factor that combines tensile, shear, and bending stresses to assess the weld’s overall strength. Permissible stresses are calculated based on the material’s yield and tensile strengths, ensuring that the weld can withstand applied loads without failure.

3. Geometric and Dimensional Checks:

   • Dimensional parameters such as weld throat thickness and weld area are verified automatically to meet Eurocode’s geometry requirements. For fillet welds, SDC Verifier assumes a weld angle of 0° in calculations, a conservative assumption that provides additional safety.

Step 5: Comprehensive Reporting in Steel Frame Verification

A clear, accurate report is essential for documenting every aspect of the verification process, from load applications to compliance checks, and it’s often a key deliverable for clients or regulatory reviews. 

What sets SDC Verifier’s reporting apart is its ability to auto-populate results directly from the analysis, including utilization factors, stress plots, and compliance metrics. This means that the report is ready to go once the verification is complete, requiring only minimal adjustments or additions. Engineers can seamlessly include visual elements like contour plots, tables, and load combination breakdowns, creating a well-rounded, professional report ready for presentation or documentation.

Furthermore, reporting features allow for easy updates. Suppose there are changes in the design or new load conditions to consider. In that case, engineers can re-run the analysis, and the report will automatically refresh with the updated results — no need to start from scratch. This dynamic reporting capability ensures documentation stays aligned with the latest data, supporting an efficient workflow for project adjustments.