CONSTRUCTION DESIGN AND SAFETY

EARTHQUAKE RESISTANT CONFINED MASONRY CONSTRUCTION

WHAT IS CONFINE MASONRY?

Basically it is a masonry confined within vertical and horizontal confining elements.

Vertical confining elements- tie columns/ practical columns.

Horizontal confining elements- tie beams. Used both in urban and rural areas.

PARTS OF CONFINED MASONRY Masonry walls Confining elements Slabs Plinth band foundation

Confined Masonry is a construction system where the walls are built first, and the columns and beams are poured in afterwards to enclose (confine) the wall.

an opportunity for improved seismic an opportunity for improved seismic performance both for unreinforced masonry and reinforced concrete frame construction in low and Medium rise buildings

WHY IT IS NEEDED? Current seismic design = strength-based approach. Performance of RCC and confined masonry in past

earthquakes. No extra skill or cost of construction The goal is to achieve enhanced seismic

performance using technologies which require similar (preferably lower) level of construction skills and are economically viable.

DIFFERENCE FROM RCC CONSTRUCTION

SUMMING UP

•CONFINED MASONRY REINFORCED CONCRETE FRAME

•It’s the walls that do the work.

•That’s why they are called load bearing walls.

•It’s the columns and beams that do the work.

•Walls are only infills.

RCC CONSTRUCTIONCONFINED MASONRY CONSTRUCTION

HOW IT RESISTS EARTHQUAKE LOAD EFFECTS Masonry walls act as diagonal struts subjected to

compression. Reinforced concrete confining members act in

tension and/or compression, depending on the direction of lateral earthquake forces.

T C

Under severe earthquake ground shaking, the collapse of confined masonry buildings may take place due to soft storey effect

This soft storey effect can be reduced using lintel ties at ground floor for extra reinforcement.

TYPES OF FAILURES IN CONFINED MASONRY SHEAR FAILURE

FLEXURAL FAILURE

KEY FACTORS INFLUENCING SEISMIC RESISTANCE OF CONFINED MASONRY STRUCTURES

Wall Density: more wall density= less damage Masonry Units and Mortar: solid and sound

brick, with good quality mortar. Tie-Columns: provision of ductility at ends. Horizontal Wall Reinforcement: beneficial

effect on wall ductility.

Openings: should be less than 10%.

WORLD WIDE APPLICATION Evolved though an informal process based on

its satisfactory performance in past earthquakes

The first reported use in the reconstruction after the 1908 Messina, Italy earthquake (M 7.2) - death toll 70,000

Practiced in Chile and Columbia since 1930’s and in Mexico since 1940’s

CHILE

COMBODIA

Currently practiced in several countries/regions with high seismic risk, including Latin America, Mediterranean Europe, Middle East (Iran), South Asia (Indonesia), and the Far East (China).

February 2010, Chile ; M 8.8 521 deaths (10 due to confined masonry construction)

INDONESIA IRAN

EL SALVADOR ARGENTINA

INSTITUTES NEW BUILDING FOR MEDICAL RESEARCH AT NAGGAR, HIMACHAL PRADESH

Made by using confined masonry (dhajji diwari system as locally called).

CONCLUSIONS It does not require highly qualified labour. due to its smaller member sizes and the lesser

amount of reinforcement it is more cost-effective than RC frame construction.

It has a broad range of applications - it can be used for single-family houses as well as for medium-rise apartment buildings.

Confined masonry construction has a great potential for saving lives and property in areas of high seismic risk in India, where more than 5 crore of population belongs to middle class and 41.6% population is below poverty line (2010 census) .

THANK YOU

Presented by- Hemant Kumar, VII sem , Architecture and Planning, VNIT Nagpur.

Q & A