This standard provides guidelines for the seismic evaluation, repair, and strengthening of existing masonry buildings. It establishes a procedure for assessing damage, determining seismic vulnerability, and selecting appropriate retrofitting strategies to enhance the building's resistance to future earthquakes.
Seismic Evaluation, Repair and Strengthening of Masonry Buildings - Guidelines
Quick Reference Values
Minimum compressive strength of cement-sand grout10 MPa
Minimum thickness of concrete jacket layer40 mm
Minimum grade of concrete for jacketingM15
Minimum diameter of reinforcing bars for splints and bandages8 mm
Maximum slenderness ratio (h/t) for load bearing walls20 for one or two storeys, 12 for more storeys
Key Formulas
SSI = C / D — Structural Safety Index, where C is lateral strength capacity and D is lateral strength demand
Practical Notes
This is a guideline document; engineering judgment is paramount, especially for heritage structures.
The primary goal of strengthening is to ensure 'box action' by connecting walls, floors, and the roof, thereby improving the building's overall integrity.
A thorough diagnosis of damage is crucial. Not all cracks are seismic; some may be due to settlement, thermal effects, or material degradation.