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CONFINED MASONRY vs.RC FRAME WITH MASONRY

INFILL

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This Guideline is for Single Story

Confined Masonry Houses withLightweight (Flexible) Roofs

Well-designed and built confinedmasonry buildings can perform well inearthquakes.

However, if they are designed and builtpoorly, they can be deadly.

Even a well built confined masonrybuilding will probably have cracks in astrong earthquake.

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Which structural system are you using?

RIGID wall should bestiff under seismicloading

DUCTILE frame shouldbe flexible under seismicloading

StructuralSystem

Confined MASONRY WALL(shear wall)

FRAME (columns andbeams)

SeismicLoad

Load bearing confined

MASONRY WALL

FRAME (columns and

beams)

Gravity

Load

Confined MasonryFrame with Masonry InfillRC

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Which structural system are you using?

Ductile detailing NOT

REQUIRED in columnsand beams, usuallydone empirically(smaller sections,

smaller bar diameters,fewer stirrups) Beamsand columns areconfining elementsacting in tension butCONNECTIONS areCRITICAL

Ductile detailing and

design required incolumns and beams(larger sections, largerdiameter steel bars,

more stirrups at closerspacing)

Beam

andColumnDesign

RC Confined MasonryRC Frame withMasonry Infill

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Which structural system are you using?

MASONRY WALL

constructed first

FRAME (columns and

beams) constructed first

Process

STRUCTURAL SHEARWALL qualityworkmanship is

critical, as isattachment to the tiecolumns and bondbeams

NONSTRUCTURAL forspace partitioning,generally not attached to

frame, but should berestrained from fallingout (lightweight materialbest masonry infill can

have a negative effecton frame)

Infill /

Wall

RC Confined MasonryRC Frame with MasonryInfill

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In Confined Masonry, Bond Beams are Not True Beams they areuniformly supported by strip footing or masonry wall

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Be Careful These Beams Are Beams and Require Ductile

Detailing

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This Guideline Does Not Apply to RC

Frame and RC Stilt Structures FRAME structures must be

engineered, designed,detailed, and are beyond thescope of this guideline

If you are building a framestructure, consider replacingthe heavy brick masonry infillwith a lighter weight material,and restrain it from falling in

an earthquake Reinforced concrete stilt-type

structures with heavy massabove the plinth beam, andthose with open first floor and

heavy second floor, should beavoided in earthquake-proneregions, especially wheresoft/loose soil conditions exist

Inadvisable designs for

earthquake-prone regions

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Build Changes Philosophy

Design/Build Houses which are

1. Safe (earthquake-resistant)

2. Satisfactory (culturally appropriateand comfortable for homeowners)

3. Sustainable (built with locally

available materials, tools and skills,affordable)

the three Ss

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Which structural system are you using?

LowerHigherCost

LessMoreEngineeringInputRequired

LowerHigherSkill ofWorkers

Single story

houses and smallshops

Multistory commercial

buildings, schools,mosques, 2-story housesfor wealthier residents

Uses in

Indonesia

RC ConfinedMasonry

RC Frame with MasonryInfill

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Build Changes Philosophy

Make low or no-cost improvements toexisting, common ways of building

Confined masonry is the most commonmethod currently being used byhomeowners to build single story

homes in Sumatra and Java

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Basic Concept of Confined Masonry

Masonry walls confined on all four sides byreinforced concrete members bond beams(sloof ring balok) and tie columns (kolom

utama kolom praktis) Reinforced concrete members are

interconnected connection is critical

Masonry walls constructed first, tie columnsand bond beams cast around masonry walls

Walls assumed to carry all vertical and lateralloads.

Contribution of tie column and bond beam tothe strength and load resistance is not takeninto account.

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This is a GUIDELINE because no building code

adequately addresses confined masonryspecific to Acehnese materials andarchitectural preferencesSingle story: most codes and guidelines deal

with multiple stories with heavy roof and floorsso are overconservative for single storystructures with lightweight roofs

Tall, slender wall: most building codesrecommend a lower height to thickness ratio

Large, tall openings: most building codesrecommend smaller openings

Timber truss roof: acts as a flexible diaphragm,potential for out-of-plane failure must bemitigated in other ways

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The Most Important Factors for Good

Performance of Confined MasonryBuildings in Earthquakes Are

1.Configuration

2.Connections

3.Construction Quality(Materials and Workmanship)

the three Cs