IS sp Part 38 — Handbook of Typified Designs for Structures with Steel Roof Trusses (With and Without Cranes) (Based on IS Codes)

IS SP Part 38: Introduction - Key Points

IS SP Part 38 is a specialized code published by the Central Public Works Department (CPWD), New Delhi, focusing on specific structural engineering practices.

Key Highlights:

• Scope: Provides guidelines for design, construction, and quality control of specialized structures or materials.
• Purpose: Ensures uniformity and safety in public works projects.
• Application: Used by engineers and architects in government projects.

Typical Content (General IS Code Practice):

• Definitions and terminology.
• Design principles.
• Material specifications.
• Load considerations.
• Safety factors.

Commonly Referenced Formulas:

• Load calculations: ( P = w \times A ) where ( P ) = load, ( w ) = load intensity, ( A ) = area.
• Stress: ( \sigma = \frac{F}{A} ) (force over area).
• Bending moment and shear force relationships.

Tables (Usually Included):

• Material properties (e.g., concrete grade, steel yield strength).
• Load factors and combinations.
• Permissible stresses.

For detailed formulas and tables, refer to the specific clauses within IS SP Part 38 as it varies per subject covered.

flowchart TD
    A[Introduction] --> B[Scope]
    A --> C[Purpose]
    A --> D[Application]
    A --> E[Design Principles]
    A --> F[Material Specs]
    A --> G[Load Considerations]
    A --> H[Safety Factors]

IS SP Part 38: Scope Overview

IS SP Part 38 is a specialized code under the Central Public Works Department (CPWD) focusing on structural design and detailing for specific construction materials or techniques.

Key Points on Scope:

• Defines applicability to particular structures/materials (e.g., masonry, steel, concrete).
• Specifies design principles aligned with safety, serviceability, and durability.
• Covers construction practices, load considerations, and material specifications.
• Integrates with relevant IS codes for comprehensive design (e.g., IS 456 for concrete).

Typical Specifications:

Example Formula (Structural Load Calculation):

[ P_u = 1.5 \times (D + L) ] Where:

• (P_u) = Ultimate load
• (D) = Dead load
• (L) = Live load

For precise scope details, refer to the introductory clauses of IS SP Part 38 and related IS codes.

flowchart TD
    A[IS SP Part 38 Scope] --> B[Materials]
    A --> C[Loads]
    A --> D[Design Methods]
    A --> E[Detailing]
    A --> F[Testing & Quality Control]

IS SP 38 Part 38 relates to load considerations for structural design. Though the specific clause is not provided, key load considerations generally follow IS 875 (Part 1 to 5). Here's a concise summary:

Key Load Considerations (per IS 875 series):

• Dead Load (DL): Self-weight + fixed components.

• Live Load (LL): Variable loads as per occupancy (IS 875 Part 2).

• Wind Load (WL): Calculated using:

  [ P = 0.6 \times V^2 \times k_1 \times k_2 \times k_3 \times A ]

  Where:

  • (V) = Basic wind speed (m/s)
  • (k_1) = Terrain/height factor
  • (k_2) = Structure size factor
  • (k_3) = Direction factor
  • (A) = Projected area (m²)

• Seismic Load: As per IS 1893, based on seismic zone, soil type, and importance factor.

Typical Load Factors (IS 875 Part 5):

Summary:

• Use IS 875 for load magnitudes.
• Apply load factors from IS 875 Part 5.
• Combine loads per load combination rules in IS 875.
• Refer to IS 1893 for seismic loads.

flowchart LR
    A[Dead Load] --> C[Load Combination]
    B[Live Load] --> C
    D[Wind Load] --> C
    E[Seismic Load] --> C
    C --> F[Design Load]

For detailed tables and factors, consult IS 875 and IS 1893 directly.

IS SP 38 Part 38 focuses on typified truss designs used in public works. Although the code does not provide explicit tables or formulas, key parameters and typical design aspects are as follows:

Key Parameters for Typified Truss Designs

• Span Length (L): Commonly ranges from 6m to 30m.
• Truss Depth (d): Usually 1/8 to 1/10 of the span.
• Panel Points: Number of panels typically 6 to 12.
• Member Sizes: Based on axial load calculations using IS 800.

Typical Design Formulas

• Axial Force in Members: [ F = \frac{P \times L}{4 \times \text{sin}(\theta)} ] where (P) = load, (L) = span, (\theta) = angle of member.

• Buckling Check for Compression Members: [ \sigma_c = \frac{P}{A} \leq f_{cd} ] where (f_{cd}) = design compressive strength.

Common Truss Types

• Pratt Truss
• Warren Truss
• Howe Truss

Typical Panel Arrangement Diagram

graph LR
A[Support] -- Top Chord --> B -- Panel Point --> C -- Panel Point --> D[Support]
A -- Bottom Chord --> E -- Panel Point --> F -- Panel Point --> D
B -- Diagonal --> F
C -- Diagonal --> E

For detailed member sizing, refer to IS 800 for steel design and IS 875 for loading. Use load combinations as per IS 875 Part 1 & 2.

IS SP 38 Part 38 (Analysis of Truss Members) provides guidelines for determining forces in truss members using classical methods.

Key Formulas:

• Method of Joints:
  For equilibrium at a joint,
  [ \sum F_x = 0, \quad \sum F_y = 0 ]

• Method of Sections:
  Cut through the truss and apply equilibrium:
  [ \sum F_x = 0, \quad \sum F_y = 0, \quad \sum M = 0 ]

• Force in a member (tension/compression):
  [ F = \frac{P \times \text{distance}}{\text{member length}} ]

Typical Specifications:

• Truss members are assumed pin-jointed.
• Loads are applied only at joints.
• Members are two-force members (axial force only).

Common Tables (from IS codes):

graph TD
    A[Joint] -->|Fx=0| B[Horizontal Force]
    A -->|Fy=0| C[Vertical Force]
    A -->|Equilibrium| D[Member Forces]

For detailed design, refer to IS 800 and IS 875 for loadings and safety factors.

IS SP 38 Part 38 covers design of purlins and girts in steel structures. Key points:

Design Considerations:

• Purlins/girts are laterally supported beams subjected to bending and shear.
• Design for bending moment, shear, and deflection.
• Check lateral-torsional buckling and local buckling.

Key Formulas:

• Bending Stress,
  [ f_b = \frac{M}{Z} ]
  where (M) = bending moment, (Z) = section modulus.

• Shear Stress,
  [ f_v = \frac{V}{A_v} ]
  where (V) = shear force, (A_v) = shear area.

• Deflection,
  [ \delta = \frac{5 w L^4}{384 E I} ]
  for uniformly distributed load (w), span (L), modulus of elasticity (E), moment of inertia (I).

Specifications:

• Use cold-formed or hot-rolled sections as per IS 801.
• Spacing and support conditions per IS 800.
• Limit deflection to span/180 or as specified.
• Provide lateral bracing to prevent buckling.

Tables:

• Section properties (Z, I, A_v) for standard purlin/girt sections are given in IS 801.
• Allowable stresses per IS 800.

flowchart TD
    Load[Load on Purlin/Girt]
    BendingMoment[Bending Moment (M)]
    ShearForce[Shear Force (V)]
    SectionProps[Section Properties (Z, Av, I)]
    StressCalc[Calculate Stresses]
    DeflectionCalc[Calculate Deflection]
    BucklingCheck[Check Buckling]
    Design[Final Design]

    Load --> BendingMoment
    Load --> ShearForce
    BendingMoment --> StressCalc
    ShearForce --> StressCalc
    SectionProps --> StressCalc
    SectionProps --> DeflectionCalc
    StressCalc --> BucklingCheck
    DeflectionCalc --> BucklingCheck
    BucklingCheck --> Design

For detailed design, refer IS SP 38 Part 38 along with IS 800 and IS 801.

IS SP 38 Part 38 (Guide for Design of Cantilever Columns) provides key guidelines for cantilever column design, supplementing IS 456.

Key Design Aspects:

• Cantilever columns are subjected to bending moments and axial loads.
• Design must consider combined axial load and bending moment.
• Effective length for lateral buckling is critical.

Important Formulas:

1. Design axial load (P_u):
   ( P_u = 0.4 f_{ck} A_c + 0.67 f_y A_s )

2. Moment capacity (M_u):
   Use interaction curves from IS 456 or calculate moment capacity considering eccentricity.

3. Slenderness ratio (λ):
   [ \lambda = \frac{L_{eff}}{r} ] where ( L_{eff} ) = effective length, ( r ) = radius of gyration.

4. Buckling check:
   Use Euler’s formula or IS 456 Clause 6.2.3 for slender columns.

Typical Specifications:

• Minimum reinforcement as per IS 456.
• Provide lateral ties/stirrups to prevent buckling.
• Use M20 or higher grade concrete.
• Effective length depends on boundary conditions (fixed, free).

Simplified Interaction Diagram (Moment vs Axial Load):

graph LR
A[Pure Axial Load] -- No Moment --> B[Pure Bending]
A -- Increasing Moment --> C[Interaction Curve]

For detailed design, refer to IS 456 interaction curves and IS SP 38 recommendations.

IS 875 (Part 3): Wind Loads is the relevant code for wind load calculations, often referenced alongside IS SP 38.

Key Formulas for Wind Load (IS 875 Part 3)

• Design Wind Pressure:

[ P = 0.6 \times V_z^2 \times C_d \times C_e \times C_s ]

Where:

• (P) = design wind pressure (kN/m²)

• (V_z) = design wind speed at height (z) (m/s)

• (C_d) = drag coefficient (depends on shape)

• (C_e) = exposure factor (depends on terrain category)

• (C_s) = size factor (for large structures)

• Basic Wind Speed (V_b) is given in IS 875 Part 3 Table 1 (varies by location).

Load Combinations (IS 875 Part 5 / IS 456)

Typical load combinations including wind load:

Exposure Categories (IS 875 Part 3)

flowchart LR
    A[Basic Wind Speed \(V_b\)] --> B[Exposure Factor \(C_e\)]
    B --> C[Design Wind Speed \(V_z\)]
    C --> D[Calculate Wind Pressure \(P\)]
    D --> E[

IS SP:38 (Part 38) covers Member Sizing and Selection for structural elements, focusing on efficient design and safety.

Key Formulas for Member Sizing:

• Axial Load Capacity (P):
  [ P = A \times f_y ]
  Where:

  • (A) = Cross-sectional area
  • (f_y) = Yield strength of material

• Bending Moment Capacity (M):
  [ M = Z \times f_y ]
  Where:

  • (Z) = Section modulus

• Slenderness Ratio ((\lambda)) for columns:
  [ \lambda = \frac{L_{eff}}{r} ]
  Where:

  • (L_{eff}) = Effective length
  • (r) = Radius of gyration

Typical Tables Include:

Specifications:

• Select members ensuring slenderness ratio is within limits (IS 800 guidelines).
• Use effective length factors based on end conditions.
• Check combined stresses for axial + bending using interaction formulas.

flowchart TD
    A[Determine Loads] --> B[Select Section Type]
    B --> C[Calculate Section Properties (A, I, Z, r)]
    C --> D[Check Axial Capacity]
    C --> E[Check Bending Capacity]
    D & E --> F[Check Slenderness Ratio]
    F --> G{Pass?}
    G -- Yes --> H[Finalize Member]
    G -- No --> B

For detailed tables and interaction curves, refer to IS 800 and IS SP:38 Part 38 annexures.

IS SP 38 (Part 38) covers structural design aspects, including reaction forces and bending moments. Although the clause isn't specified, here are key general formulas and concepts used for reaction forces and bending moments in beams:

Reaction Forces

• For a simply supported beam with point load (P) at distance (a) from left support: [ R_A = \frac{P (L - a)}{L}, \quad R_B = \frac{P a}{L} ]
• For uniformly distributed load (w) over length (L): [ R_A = R_B = \frac{wL}{2} ]

Bending Moments

• At any section (x) from left support under point load (P): [ M_x = R_A x - P (x - a) \quad \text{for } x > a ]
• Maximum bending moment for point load at center: [ M_{max} = \frac{P L}{4} ]
• For uniformly distributed load: [ M_{max} = \frac{w L^2}{8} ]

Table: Common Beam Loading Cases (Simply Supported)

These formulas align with IS 456 and IS 800 practices referenced in IS SP 38.

graph LR
A[Load P at distance a] -->|Reactions| B[Calculate R_A and R_B]
B --> C[Bending Moment at x]
C --> D[Max Bending Moment]

For precise design, refer to IS SP 38 Part 38 tables and examples.

IS SP 38 Part 38 covers Base Plate and Column Support Design with key considerations as follows:

Key Design Aspects:

• Base Plate Thickness (t): Ensure adequate thickness to prevent local buckling.
• Bearing Pressure (q): Should not exceed soil or grout bearing capacity.
• Anchor Bolt Design: To resist uplift and shear forces.
• Plate Size: Sufficient to distribute column load uniformly.

Important Formulas:

1. Bearing Pressure on Base Plate: [ q = \frac{P}{A} \leq q_{allow} ] Where:

   • (P) = Axial load on column
   • (A) = Area of base plate in contact with concrete/grout
   • (q_{allow}) = Allowable bearing pressure

2. Base Plate Thickness (t): [ t = \sqrt{\frac{M}{f_y \times Z}} ]

   • (M) = Moment at column base
   • (f_y) = Yield strength of base plate steel
   • (Z) = Section modulus of base plate cross-section

3. Anchor Bolt Design:

   • Tensile capacity based on bolt diameter and material.
   • Shear capacity per IS 1367.

Typical Table for Base Plate Thickness (Example):

Specifications:

• Use Grade Fe 410 steel for base plates.
• Provide minimum 50 mm bearing length beyond column flange.
• Ensure grout thickness of 10-20 mm under base plate.

flowchart TD
    A[Column Load P] --> B[Base Plate]
    B --> C{Bearing Pressure q = P/A}
    C -->|q ≤ q_allow| D[Safe Design]
    C -->|q > q_allow| E[Increase Plate Size]
    B --> F[Anchor Bolts]
    F --> G[Design for Tension & Shear]

For detailed design, refer to IS SP 38 Part 38 and

IS SP Part 38 (Design Examples and Tables) serves as a supplementary guide to IS codes, offering practical design illustrations and tabulated data for structural engineers.

Key Features:

• Design Examples: Step-by-step solutions for typical structural elements (beams, columns, slabs) based on IS 456, IS 800, etc.
• Tables: Quick reference for material properties, load factors, reinforcement detailing, and permissible stresses.
• Specifications: Standardized dimensions, load combinations, and safety factors aligned with central government norms.

Typical useful tables include:

Example formula for design moment (flexure):

[ M_u = f_{ck} \times b \times d^2 \times k ]

Where:

• (M_u) = Ultimate moment capacity
• (f_{ck}) = Characteristic compressive strength of concrete
• (b) = Width of the section
• (d) = Effective depth
• (k) = Coefficient from IS code tables

For detailed design, refer to worked examples in IS SP 38 aligned with IS 456 and IS 800 provisions.

flowchart TD
    A[Start: Structural Element] --> B{Select Code}
    B -->|IS 456| C[Concrete Design Example]
    B -->|IS 800| D[Steel Design Example]
    C --> E[Use Tables for Material Properties]
    D --> E
    E --> F[Calculate Loads & Moments]
    F --> G[Apply Safety Factors]
    G --> H[Design Reinforcement]
    H --> I[Check Serviceability & Strength]
    I --> J[Complete Design]

IS SP 38 Part 38 (Guidelines for Analysis and Design of Structures) provides essential notes on analysis and design, focusing on practical structural engineering.

Key Points on Analysis and Design:

• Analysis Methods: Use appropriate methods (e.g., Elastic, Plastic, or Finite Element Analysis) depending on structure complexity.
• Load Considerations: Combine loads as per IS 875 (Dead, Live, Wind, Seismic).
• Material Properties: Use characteristic strengths from IS codes (e.g., IS 456 for concrete, IS 800 for steel).
• Factor of Safety: Apply partial safety factors as per relevant codes.
• Deflection Limits: Ensure deflections are within permissible limits to avoid serviceability issues.
• Stability Checks: Check for buckling, lateral-torsional buckling, and overall stability.
• Redundancy and Ductility: Design for alternate load paths and ductile behavior where applicable.

Typical Design Formulae:

• Bending Stress:
  [ \sigma = \frac{M}{Z} ] where ( M ) = bending moment, ( Z ) = section modulus.

• Axial Stress:
  [ \sigma = \frac{P}{A} ] where ( P ) = axial load, ( A ) = cross-sectional area.

• Combined Stress (for axial + bending):
  [ \sigma = \frac{P}{A} \pm \frac{M}{Z} ]

Common Tables (Refer IS 456, IS 800):

flowchart LR
    A[Load Application] --> B[Structural Analysis]
    B --> C{Type of Analysis}
    C --> D[Elastic Analysis]
    C --> E[Plastic Analysis]
    C --> F[Finite Element Analysis]
    D --> G[Calculate Stresses & Deflections]
    E --> G
   

IS SP 38 Part 38 does not specify direct formulas or tables for "References to IS Codes." However, general practice for referencing IS codes in structural design involves:

• Use Latest Editions: Always refer to the latest versions of IS codes for design and construction.
• Common IS Codes for Structural Engineering:
  • IS 456: Plain and Reinforced Concrete – Code of Practice
  • IS 800: General Construction in Steel – Code of Practice
  • IS 1893: Criteria for Earthquake Resistant Design of Structures
  • IS 875: Code of Practice for Design Loads (Dead, Live, Wind, Seismic)
  • IS 13920: Ductile Detailing of Reinforced Concrete Structures
• Referencing Format:
  IS <code number> : <year> - <title>

Example Table for Common IS Codes

For detailed design, cross-reference relevant IS codes as per the project scope.

graph LR
A[Structural Design] --> B[Load Calculations (IS 875)]
A --> C[Material Design (IS 456, IS 800)]
A --> D[Seismic Design (IS 1893, IS 13920)]

Summary: Use IS SP 38 Part 38 as a guideline for referencing, but rely on specific IS codes for detailed formulas and specifications.

IS SP Part 38 pertains to guidelines for structural design and detailing, but the provided context lacks direct details on Annexures.

General Guidance on Annexures in IS Codes:

• Annexures typically include design formulas, tables, and examples for quick reference.
• They provide material properties, load factors, and sectional properties.
• Often include standardized detailing and construction specifications.

Common Key Elements in Annexures (General Structural Codes):

Example: Basic Flexural Design Formula

[ M_u = 0.87 f_y A_s (d - \frac{a}{2}) ]

• (M_u) = Ultimate moment
• (f_y) = Yield strength of steel
• (A_s) = Area of tension reinforcement
• (d) = Effective depth
• (a) = Depth of equivalent stress block

For exact Annexure content, refer to the official IS SP Part 38 document or CPWD manuals.