The 1988 edition of IS SP Part 47 serves as an exhaustive reference for the structural design and evaluation of steel lattice portal frames devoid of crane systems. It addresses the behavior of these structures under various loading scenarios including permanent, imposed, wind, and seismic forces, emphasizing both short and long-span configurations. This guideline is indispensable for engineers and designers committed to safe, code-compliant steel lattice portal frame constructions in India.
Overview
The 1988 edition of IS SP Part 47 serves as an exhaustive reference for the structural design and evaluation of steel lattice portal frames devoid of crane systems. It addresses the behavior of these structures under various loading scenarios including permanent, imposed, wind, and seismic forces, emphasizing both short and long-span configurations. This guideline is indispensable for engineers and designers committed to safe, code-compliant steel lattice portal frame constructions in India.
Audience
Contents
Structure
Includes calculations for live load and basic wind load as per IS 875 and IS SP 47, along with key wind load and foundation force tables for various configurations.
Details analysis methods such as moment distribution and matrix stiffness, frame geometries, member sizing, and design load combinations.
Covers member design parameters, load adjustment factors, and typical section selections based on roof slopes and wind pressures.
Specification of eaves beam slenderness limits, recommended sections, connection details, and typical load data.
Explains calculation of foundation forces under various load cases, base conditions, design combinations, and typical foundation types.
Describes wind load scenarios, pressure/suction influences, load tables, and design formulas per IS codes.
Discusses lateral load effects, seismic force estimation, load application, and integration with wind and dead loads following IS 1893.
Presents stress limits for axial and bending loads, load combination multipliers, and stress check formulas.
Summarizes sizes and specifications for haunch, crown, lacing, and base plate connections, including weld and bolt requirements.
Provides design force adjustment guidelines and tabulated member sizes, forces, and weights for practical design scenarios.
Details calculation for anchor bolt embedment, bolt sizing, number requirements, and base plate anchorage considerations.
Includes frame parameters, member forces, moments, sway data, and wind load calculation formulas.
Frequently Asked
The standard specifies that design must consider combinations of Dead Load (DL), Live Load (LL), Wind Load (WL), and Earthquake Load (EQ). It outlines three main wind scenarios—wind perpendicular to the ridge with internal suction (WL1), wind perpendicular with internal pressure (WL2), and wind parallel with internal pressure (WL3). Typical load combinations include DL + LL, DL + WL1, DL + WL2, DL + WL3, DL + LL + maximum wind load, and DL + EQ, with forces multiplied by 1.33 when DL + WL governs to account for increased allowable stresses.
IS SP 47 integrates wind load effects by considering three distinct cases that include internal pressure or suction effects based on building permeability. Internal pressures are taken as ±0.2 times the basic wind pressure for normally permeable structures. The wind load cases cover wind directions both perpendicular and parallel to the ridge and differentiate between suction and pressure conditions, affecting member forces significantly. Designs are based on the most critical of these scenarios.
Specific member sizes and lacing details depend on frame span, column height, and roof slope. Typical lacing sections range from 40×40×6 mm to 110×110×10 mm ISA angles, with spacing between 500 mm and 900 mm. Columns and rafters utilize lacing angles and rods sized according to load requirements and buckling lengths, with comprehensive tables provided for selecting appropriate sections based on span and wind conditions.
Foundation forces are derived by combining Dead Load, Live Load, and Wind Load effects, with a multiplication factor of 1.33 applied to DL + WL combinations when they govern. The standard offers detailed tables listing axial forces, shear forces, and moments at foundations for varied spans, slopes, and wind pressures. Design involves selecting relevant frame parameters, referring to tabulated forces, and applying appropriate load factors for foundation sizing.
Yes, the handbook includes seismic design considerations by treating earthquake loads as lateral forces similar to wind loads. It provides analysis methods, load combinations, and force calculations aligned with IS 1893 seismic code provisions. Design incorporates axial, bending, and shear forces induced by seismic effects, addressing various seismic zones and structural configurations to ensure stability and compliance.
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