PEB section Estimation calculator

PEB tentative section Estimation

Span ($L$) [m]

Bay Spacing [m]

Eave Height [m]

Base Connection Pinned (Standard) Fixed (Rigid)

Wind Speed ($V_b$) 33 m/s (Low) 44 m/s (Medium) 50 m/s (High/Coastal)

Primary Geometry

Optimum Max Depth	--
Min Web Thickness	--
Flange Width	--
Deflection Limit ($L/180$)	--

Anchor & Shear Key

Anchor Bolts	--
Embedment ($15 \times d$)	--
Shear Key Req.	--
Key Size (Approx)	--

Design Logic & Weight

Est. Steel: MT/bay

PEB Structural Member Estimation Tool – Technical Explanation

This tool is developed for Pre-Engineered Building (PEB) preliminary design. It provides quick and reliable estimates of structural member sizes, anchor systems, and steel weight based on standard engineering thumb rules and practical industry experience.

1. Objective of the Tool

The primary objective is to assist engineers in obtaining:

• Preliminary rafter depth and plate sizes
• Steel quantity estimation
• Anchor bolt requirements
• Shear key necessity check
• Basic design validation using engineering logic

2. Input Parameters

• Span (L): Distance between columns
• Bay Spacing (B): Distance between frames
• Eave Height (H): Height at column top
• Base Connection: Pinned or Fixed
• Wind Speed (Vb): Governing lateral load parameter

3. Primary Member Design Logic

3.1 Rafter Depth Estimation

The tool uses a widely accepted optimization ratio:

d ≈ L / 28

Where:

• d = depth of rafter (mm)
• L = span (mm)

This ensures:

• Efficient bending resistance
• Economical steel usage
• Compliance with deflection limits

3.2 Web Thickness

tw = d / 150 (minimum 6 mm)

This criterion ensures:

• Shear capacity adequacy
• Prevention of web buckling

3.3 Flange Width

bf = d / 5 (minimum 150 mm)

Flange width governs:

• Bending strength
• Lateral torsional stability

3.4 Deflection Check

Allowable Deflection = L / 180

This is a standard serviceability limit used in industrial structures.

4. Steel Weight Estimation

The steel consumption is estimated using empirical relationships:

kg/m² = 25 + (0.5 × L) + Wind Factor

Where:

• Base value = 25 kg/m² (light structure)
• Span effect increases steel
• Wind factor adds 10 kg/m² for high wind zones

Total Steel (MT) = (kg/m² × L × B) / 1000

This gives steel per bay, useful for:

• Cost estimation
• Feasibility studies

5. Anchor Bolt Design Logic

Bolt Diameter Selection

If L > 30 m → M30 bolts Else → M24 bolts

Bolt Quantity

Pinned Base → 4 bolts Fixed Base → 8 bolts

Embedment Depth

Embedment = 15 × Bolt Diameter

This ensures proper anchorage and pull-out resistance.

6. Shear Key Requirement

Shear key necessity is checked using friction vs shear condition:

If Vu > μ × Pu → Shear Key Required

Simplified logic used in the tool:

• High wind (≥ 44 m/s) OR large span (> 35 m) → Shear key required
• Otherwise friction is sufficient

Typical Shear Key Sizes

• ISMC 150 channel
• 100 × 100 box section

7. Role of MathJax

The tool integrates MathJax to dynamically render engineering equations such as:

• Depth optimization formulas
• Weight calculations
• Design inequalities

This improves readability and provides a professional engineering interface.

8. Engineering Assumptions

• Preliminary design only (not final design)
• Uniform loading conditions
• Standard material properties
• Typical industrial building configuration

9. Limitations

• Does not replace detailed structural analysis
• No seismic load consideration
• No connection design verification
• No code-specific checks (IS 800, MBMA, etc.)

10. Conclusion

This PEB estimation tool serves as a fast and practical design assistant for structural engineers. It bridges the gap between conceptual design and detailed analysis, helping engineers make informed decisions quickly.

For final design, it is recommended to validate results using detailed structural analysis software and relevant design codes.