Alam Md. NurulSenior Structural Engineer, ADPC

Senior Structural Engineer

Construction Practices : The Good, The Bad & The Ugly!

(Case studies)

The only alternative to risk management is crisis management --- and crisis management is much more expensive, time consuming and embarrassing.

JAMES LAM, Enterprise Risk Management, Wiley Finance © 2003

Without good risk management practices, government cannot manage its

resources effectively. Risk management means more than preparing for

the worst; it also means taking advantage of opportunities to improve

services or lower costs.Sheila Fraser, Auditor General of Canada

Why do we need Risk Management?

The column sizes were comparatively small, compared to a standard 8-9 storied Industrial

building, which might facilitated the sudden collapse.

Building Collapse in Savar

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Heavy Overhang The presence of heavy overhang is another major cause to as appeared from

the original shape of the building (Please see photo). This might have caused the failure of the

on the upper floors of the building.

Source: The Daily Star

6’ Heavy Overhang

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ok

A Fatal Crack & Progressive Collapse

It was the rebar or the cement that

might be insufficient, for which a crack

was spotted on Rana Plaza's seventh

floor by workers on Tuesday, a day

before it collapsed. News media

reported that cracks had been

discovered in the building the day before

and people were requested to evacuate

the building. The shops and the bank on

the lower floors immediately closed, but

garment workers were told to return the

following day, their supervisors declaring

the building to be safe. The crack might

be due to lack of sufficient

reinforcement, since the collapse was

sudden and brittle in nature. The top

floor fell on the floor beneath and the

impact was too strong for the lower

story to withstand, and the entire

structure collapsed, [3] which might show

the characteristics of progressive

collapse.

A Fatal Crack followed by the progressive collapse happened due to heavy weights from 6 Generators and also from Industrial Use

Collapse of 4 storied building in Begunbari, 2010

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Occurs when first story

much less stiff than

stories above

Typical damage –

collapse of first story

Gujarat EQ

Soft story

13

Soft Storey

14

Soft Storey

15

Soft Storey

Without soft storey

Soft storey

Effects of 1997 Earthquake

HOUSES, GOOD AND BADFor shape of the house, the simpler and more symmetrical the better. When lateral forces work to pull the building apart, shapes with roughly equally sized walls distribute that force more efficiently.

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Footing on Soft Soil

The building was located in the marshy

land which is recently filled in with

garbage and loose soil. The collapse

after shaking in the nearby buildings

gives the evidence of the low laying

areas of the surrounding communities.

Mr. Russel, a local resident said,

“people residing neighboring areas felt

a shaking effect while the building was

collapsing”. The quality of the

underneath soil may have the major contribution in the collaps

Recent infill lands Adjacent to the Collapse Site

Recently filled area

liquefaction

Poor Workmanship and use of Low Strength Materials might be another issue for the collapse.

From the site it seemed that the quality of the materials and workmanship was not complying

with the standard practice.

Poor Construction Materials Used in the Building

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• Low Strength • Brittle • Strong beam, weak column • Beam-column joint failure

Ductility

BAD BRICKEarthquake-resistant houses rely on workmanship and materials, including high-quality bricks. Build Change advises homeowners to avoid curved or warped bricks with cracks or chips

GOOD BRICK"When hit together, good bricks make a clink sound, not a dull thud," says the Build Change builder's manual.

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BAD GRAVELWhen choosing gravel for mixing concrete, crushed, angular rocks are better. Rounded rocks decrease the available bonding area for concrete particles and lessen overall strength.

GOOD GRAVELThe best kind of gravel for mixing concrete is crushed stone.

BAD MASONRYBad masonry means weak walls. Here, thedistance between bricks is uneven, thejoints between bricks are not staggered farenough apart, and the joints themselvesare not completely filled with mortar.

GOOD MASONRYHere, the bricks are horizontally straight,vertically plumb and the joints betweenbricks are 1.2 cm thick or smaller.

Building collapses on adjacent houses in Old Dhaka, 2012

(a) Collapsed portion in other

building (b)Improper Reinforcement (c)Assessment Survey (d)Narrow Stairway

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Building collapses on adjacent houses in Old Dhaka, 2012

Collapsed Portion Demolished portion by the owner

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Building collapses on adjacent houses in Old Dhaka, 2012

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Short column effectsShort column problem may arise due to arrangement of infill walls or other non-structural, architectural member. Sometimes, the infill walls are shorter than the column. The top of the walls may be opened for lightening purposes in schools, hospitals and apartments.

Vulnerability Factors

Short column effect…...

What do you think about it?

Possible further Problems in the Adjoining Areas

Neighboring Buildings .

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