This code establishes the design and construction requirements for block-type and framed foundations supporting rotary machines of medium and high frequency (e.g., steam turbines, turbo-generators). It provides criteria for dynamic analysis to prevent resonance, limit vibration amplitudes, and safely transfer dynamic loads to the supporting soil.
Lays down requirements for measuring tapes and chains used in surveying for length measurement.
Quick Reference Values
maximum cg eccentricity5% of base dimension
resonance avoidance margin±20% of operating frequency
minimum clearance from adjacent structures20 mm
minimum concrete gradeM25
Key Formulas
fn = (1 / 2π) * √(K / M) — Natural frequency of the foundation system
A = F0 / √((K - Mω²)² + (Cω)²) — Amplitude of forced vibration
Practical Notes
Database Note: The title provided in the query ('Surveying instruments') is incorrect. IS 2974 strictly covers the Design and Construction of Machine Foundations.
A continuous mat or heavily reinforced block foundation is highly recommended to provide adequate mass and damping for high-speed rotary equipment.
Always perform a block vibration test on-site to determine the dynamic soil properties (dynamic shear modulus, coefficient of elastic uniform compression) prior to detailed design.