鋼製Iビームスパン計算機
最大スパンを求める鋼製I形梁の所定の荷重に対して。この計算機は、実際の断面データベースに対して曲げ耐力とたわみ限界の両方をチェックし、実際に支配する短い方のスパンを報告します。
最大スパン
Fb = 0.66 Fy, E = 200 GPa、コンパクト断面かつ横補剛あり、自重は控除していません。予備的な断面選定のみ — 有資格技術者による確認が必要です。
最大スパンの導出方法
- 曲げから： 等分布荷重 L = √(8M/w)；中央集中荷重 L = 4M/P。
- たわみから 制限 L/n の場合：等分布荷重 L = ∛(384EI / (5wn))；中央集中荷重 L = √(48EI / (Pn))。
よくある質問
鋼製I形梁はどのくらいのスパンまで可能ですか？
断面、荷重、および許容するたわみ制限に依存します。この計算機は、曲げチェックとたわみチェックの両方から最大スパンを算出し、小さい方（実際の限界）を報告します。
通常、スパンを制限するのは強度とたわみのどちらですか？
ほとんどの床組ではたわみです。たわみはスパンの4乗に比例して増大するため、短くて軽荷重の梁を除き、曲げ限界に達する前にたわみ制限に達します。
どのような荷重を入力すればよいですか？
梁が1メートルあたりに受ける総使用荷重（死荷重：自重、スラブ、仕上げ材、および活荷重を含む）を入力してください。規定の荷重係数は適用しないでください — これは許容応力度法による使用性のチェックです。
片持ち梁にも使用できますか？
片持ち梁の荷重ケースを選択してください。同じ長さの片持ち梁は、等分布荷重下の単純支持梁よりも約9.6倍たわみが大きいため、許容スパンははるかに短くなります。
Steel I-Beam Span Calculator
Calculate the maximum allowable span, deflection, and load capacity for steel I-beams based on structural engineering principles.
Analysis Results
Beam Loading Diagram
How to Use This I-Beam Span Calculator
Understanding Steel I-Beam Span Calculation
Steel I-beams are structural elements designed to support loads across an open space. Determining the appropriate beam size requires an understanding of the relationship between:
- Span Length: The distance between supports that the beam must bridge
- Applied Load: The weight or force that the beam must support (uniform, point, or combination)
- Steel Properties: The strength and stiffness characteristics of the steel
- Deflection Limits: The maximum allowable bending of the beam under load
- Safety Factors: Additional capacity to account for unpredictable conditions
Using the Calculator for Span Analysis
- Select the I-beam type (Wide Flange, American Standard, or Bearing Pile)
- Choose a standard size from the dropdown menu
- Select the load type (uniform, point load at center, point loads at third points, or cantilever)
- Enter the total load that the beam must support
- Specify the beam span (distance between supports)
- Select the steel grade based on the material specification
- Choose a deflection limit appropriate for your application
- Set a safety factor (typically 2.0-3.0 for standard applications)
- Click "Calculate" to analyze the beam performance
Using the Beam Selection Tool
If you know your required moment, span, and load but need help selecting an appropriate beam:
- Switch to the "Select Beam" tab
- Enter your required moment capacity (or let the calculator determine this from span and load)
- Specify the required span and design load
- Select the steel grade and deflection limit
- Click "Find Suitable Beam" to receive recommendations
Interpreting the Results
The calculator provides comprehensive results, including:
- Maximum Moment: The highest bending force in the beam
- Maximum Deflection: How much the beam will bend under the specified load
- Utilization Ratio: How much of the beam's capacity is being used (should be less than 100%)
- Maximum Allowable Span: The longest span this beam can safely bridge given the load
- Maximum Load Capacity: The greatest load this beam can support over the specified span
A high utilization ratio (>80%) suggests that you should consider a larger beam for additional safety margin.
Design Considerations
When selecting an I-beam, consider these factors beyond the calculator results:
- Lateral Bracing: Unbraced beams may require larger sections to prevent lateral buckling
- Connection Details: How the beam will be fastened to supporting structures
- Dynamic Loads: Moving or vibrating loads may require additional capacity
- Environmental Factors: Exposure to corrosive environments may affect beam performance
- Local Building Codes: Always verify that your design meets all applicable building codes
Important: This calculator is a tool to assist in preliminary design. Final designs should be reviewed and approved by a licensed structural engineer.
Standard I-Beam Properties
| Designation | Depth (in) | Weight (lb/ft) | Area (in²) | Ix (in⁴) | Sx (in³) |
|---|
Common Loads for Structural Design
| Application | Typical Load (lb/ft²) | Description |
|---|---|---|
| Residential Floors | 40-50 | Living areas in houses, apartments |
| Office Floors | 50-80 | Standard office spaces |
| Retail Spaces | 75-100 | Shops, stores, light retail |
| Assembly Areas | 100-150 | Auditoriums, churches, theaters |
| Storage Areas | 125-250 | Warehouses, libraries, file rooms |
| Industrial Spaces | 150-400 | Manufacturing, workshops |
| Roof (Snow Load) | 20-40 | Varies by climate zone |
Notes on Loads:
- Live loads are temporary or movable loads such as people, furniture, and equipment.
- Dead loads are permanent loads such as the weight of the structure itself, flooring, and fixed equipment.
- Total design load should include both live and dead loads multiplied by appropriate load factors.
- Local building codes may specify different minimum design loads based on climate and locality.
- For critical applications, consult with a structural engineer to determine appropriate design loads.