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Unsupported storeys weakened school felled in San Guiliano quake

TWO STOREYS were added to the school building, destroyed in an Italian earthquake last week, without strengthening existing walls and foundations, it has emerged.

Twenty six children and three teachers died when the school collapsed during an earthquake measuring 4.8 on the Richter Scale in the village of San Giuliano Di Puglia in south east Italy.

Local engineers who spoke to NCE in Italy this week put the catastrophic collapse down to wholly inadequate design and construction of extensions to the building The school was built as a single storey structure with a wooden roof on cavity blockwork walls in 1953.

When the first extra floor was added in 1970 the original timber roof was replaced with a cavity block and concrete beam floor topped with a thin layer of screed. This common flooring method is similar to beam and pot systems in the UK but uses cavity clay tiles instead of concrete blocks.

Concrete block walls were built on top of the existing walls and a new timber roof was erected.

In 2000, a third storey was added, again with beam and cavity block floor and blockwork walls. This time a concrete framed roof was added.

'This was particularly heavy construction with beams over 250mm deep, ' said one eye witness.

According to the chief engineer of seismic survey body Servizio Sismico Nazionale, Giacomo Di Pasquale, 'no improvements were made to the walls or foundations when these extra loads were applied.

'Unlike the other buildings the school was top heavy, and this, our investigators believe, is one of the major reasons why the school was the only building to collapse so dramatically and so catastrophically.'

As NCE went to press the Italian government was reported to be launching an investigation into whether the contractor responsible for the most recent work to the school complied with Italian building codes.

But an inquiry into the earthquake as a whole is likely to focus on why San Giuliano Di Puglia was not officially classed as being in a seismic zone.

'A government report in 1998 confirmed that this whole region should be considered as a seismic risk zone - but official classification has yet to be given, ' said Di Pasquale. None of the buildings in the village was designed for seismic loading, he added.

Most of the severely damaged buildings were built from simple 'waffle section' cavity clay blocks, a form of construction that is banned in seismic zones, said Di Pasquale.

Ninety per cent of San Guiliano, known for difficult clay and silt ground conditions which have caused landslides in the past, is expected to be demolished, making at least 10,000 people homeless.

This week the Department for Civil Protection (DCP) was organising temporary shelters and basic services.

Similar construction methods have been used in many other areas across Italy posing equal levels of risk, said Fabio Brondi, civil engineer at the Department for Civil Protection.

'There are many disasters waiting to happen, as effectively the whole of Italy is a siesmic zone, ' he said.

Buildings that survived the San Giuliano earthquake were either built within the last decade or were over a hundred years old. The newer buildings had generously reinforced concrete frames with non-load bearing cavity blockwork infill walls.

Older buildings are generally robust, with thick masonry walls and more flexible lime mortar.

Seismic risk ignored

SAN GUILIANO di Paglia is in an area of the Southern Apennines mountain range known to be highly seismic.

It is surrounded by districts classified as medium risk, where earthquakes are expected to exert peak ground accelerations of 0.3g only once every 50 years.

Studies by the Italian earthquake institution the Servicio Seismico Nationale in the last 20 years have revealed a previously unknown fault system, said Dina D'Ayala, a structural engineer who has closely studied earthquakes in the Appennines and now lectures at Bath University.

But according to Massimilliano Stucchi, director of the National Institute of Physics & Vulcanology, the last earthquake anywhere close to San Giuliano was 50km away in 1805.

Records dating back to the 16th century reveal nothing to suggest San Guiliano itself was sited in an active area, he said.

lA major earthquake measuring 7.9 on the Richter scale shook Central Alaska on Sunday, cracking highways, triggering mudslides, toppling fuel tanks, and knocking a section of the Trans-Alaska oil pipeline off its supports. The earthquake began on the Denali fault, and was felt as far away as New Orleans, Louisiana. There were no major injuries.

Emergency machine gears up

EMERGENCY PLANNERS from Rome have been drafted in to help 10,000 plus people made homeless by last week's earthquake in San Guiliano Di Puglia.

More than 6,000 emergency workers co-ordinated by the national Department for Civil Protection (DCP) have been toiling 24 hours a day in wet and rainy conditions to provide shelter and essential services for those who lost their homes.

The DCP has been called in to co-ordinate the relief efforts of emergency services, utilities authorities, engineering services and voluntary groups.

Rescue workers have drawn on information about houses, public buildings and utilities drawn up to help rescue services in the event of fire or floods.

The emergency plan drawn up by the municipal authority paid little attention to earthquake risk because San Guiliano di Paglia was not classified as a seismic zone.

INFOPLUS www. promolise. com

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