Structural Failures, Part III - An Engineer's Aspect


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Wednesday, June 24, 2009

Structural Failures, Part III

Engineering a structure in which someone will live, ride, fly, or work is a tremendous responsibility. Generally the first duty recognized by Professional and Chartered engineers is to the safety of the public. As with any profession, mistakes can happen. Unfortunately, in the case of engineering structures, a small mistake can prove to be fatal. Therefore, it is often instructive to study cases where mistakes were made in order to understand and never repeat the mistake.

The following is the third installment in my collection of case studies of Structural Failures.

1986: Singapore--New World Hotel Collapse

Figure 13--Aftermath of the New World Hotel Collapse. Source: SCDF.

The Hotel New World in Singapore rapidly collapsed on March 15, 1986. Of the 50 people who were trapped beneath the rubble, 17 were rescued, while 33 were killed. The Hotel New World, actually known as the Lian Yak building, was a six-story building with a basement garage built in 1971.

Wikipedia reports that,
"An inquiry investigating the cause of the accident tested for many potential causes. Surviving sections of concrete were tested to ensure they were to proper construction standards, and it was found that they were. Even the construction work of the underground railway tunnelers who had assisted in the rescue was investigated, even though the excavations were more than 100 yards from the collapsed building. It was found they had no effect on the building's stability.

Also investigated were the various additions made to the building after its initial construction. Air conditioning systems had been constructed on the roof of the building, the bank had added a large safe, and ceramic tiles had been fixed to the building's exterior, all adding considerably to the building's weight.

It was found that the weight of these additions was inconsequential; however this line of investigation led to the discovery that the original structural engineer had made a serious error in calculating the building's dead load, the weight of the building itself. The structural engineer had calculated the building's live load, the weight of the building's potential inhabitants, furniture, fixtures and fittings. However the building's dead load was completely omitted from the calculation. This meant that the building as constructed could not support its own weight. Collapsing was only a matter of time and after the three different supporting columns had failed in the days before the disaster, the other columns, which took on the added weight no longer supported by the failed columns, could not support the building."
1993: Kuala Lumpur, Malaysia--Highland Towers Collapse

Figure 14--Block 1 of Highland Towers at Taman Hillview which collapsed on 11 December 1993. Source:

Highland Towers, constructed sometime between 1975 and 1978, consists of three 12-story high apartment buildings designated as Blocks 1, 2 and 3. Directly behind the three blocks is a fairly steep incline with a stream trying to flow west. The attraction of this place was the beautiful scenery with an panoramic view of the city of Kuala Lumpur.

On Saturday, December 11, 1993, at about 1:30 pm, after 10 days of continuous rainfall, a landslide was triggered. Mud slipped into the basement of Block 1 and shifted the entire base of the building causing the entire block to collapse. The residents were trapped inside. After days of searching, 48 people were recorded dead.

According to Wikipedia, the cause of the structural failure was improper construction of the pilings. The investigative teams found that the piling structure was too short for a building of its height.

Later the investigative team interviewed the construction company and found the contractor had reduced the depth of piling for some areas after they found that the soil conditions made piling more difficult. Investigators concluded that much of the soil at the construction site was not hard soil, but actually solid rock.

1995: Seoul, Korea--Sampoong Department Store Collapse

According to 911research,

Figure 15--Sampoong Department Store Collapse in Seoul, Korea. Source:

"On June 29, 1995 a mall in Seoul, South Korea collapsed with an estimated 1,500 people inside. In less than 20 seconds, a section of the five-story building came crashing down into the basement, killing over 500 people. The collapse of the building, which was constructed using steel-reinforced concrete pillars, was blamed on faulty construction.

The building had a number of structural modifications during its lifetime which contributed to the collapse. It was originally designed as an office building with four floors, and constructed in 1987. When it was later converted to a department store, support columns were cut away to accommodate escalators. The owner, Lee Joon, carried out these modifications over the objections of the original contractors, whom he fired and replaced.

A fifth floor was eventually added to house a restaurant. It involved installation of a heavy concrete slab. A heavy air conditioning unit was added to the building's roof, exceeding the design loads by a factor of four. Haphazard relocation of the air conditioning unit damaged the roof structure.

Prior to its collpase, the building showed cracking due to the overloading produced by the faultily-engineered fifth floor and air-conditioning unit placement."

2001: Versailles Wedding Hall, Jerusalem--Third Floor Collapse

Figure 16--Rescuers search the rubble of the dance floor of the Versailles Wedding Hall in Jerusalem, which plunged through two storys. Source:

On Thursday night, May 24, 2001, a large portion of the third floor of the Versailles Wedding Hall, located in Talpiot, Jerusalem, collapsed during the wedding celebration of Keren and Asaf Dror. As a result, 23 people fell to their deaths and approximately 380 were injured.

"Initially, the side of the building that failed was designed to be a two story structure, while the other side was designed to be three stories. Late in the construction process, it was decided that both sides of the building should be equal heights, and a third story was added to the shorter side. Unfortunately, the live load due to occupancy is typically much greater than the design load for a roof. As a result, the structure supporting the new third story was subjected to much greater loading than was originally anticipated. The effect of this error was somewhat mitigated by the construction of partitions on the floor below, which helped redistribute the excess load well such that no damage was incurred.

A few weeks before the collapse, the wedding hall owners decided to remove the partitions. With the load path eliminated, the floor above began to deflect (or sag) several inches. Generally, engineers design a structure to fail in a controlled, ductile manner so that occupants have ample warning that a collapse is imminent and can evacuate. However, the owners did not recognize this and viewed the sagging floor primarily as a cosmetic problem. Their solution was to level the floor with additional grout and fill. Unfortunately, their approach not only failed to provide additional structural capacity; it also inadvertently introduced a new and significant dead load at the weakened area.

During the wedding event in 2001, this significantly overstressed floor section failed resulting in the catastrophe. The engineer Eli Ron, inventor of the Pal-Kal method of construction, was arrested and subsequently indicted in August 2002 on the charge of manslaughter. Notably, Ron had not engaged in any part of the design or construction, but had sold proprietary elements necessary for construction that were installed in a deficient manner (Wikipedia)."

2004: Paris, France--Charles de Gaulle Airport, Collapse of the Terminal 2E Roof

Figure 17--The deadly collapse of Terminal E of the Charles de Gaulle International Airport in Paris. Source: wirednewyork.

On 23 May 2004, not long after its inauguration, a portion of Terminal 2E's ceiling collapsed, near Gate E50, killing four people and injuring three others.

"The first sign of trouble was when a long strip of concrete fell from the underside of the shell, close to the weak point where three walkways pierced the structure, along the line of the steel struts connecting concrete compression member to steel tension member ("

Ninety minutes later two almost simultaneous events occurred. The northern wall unit buckled and the struts punched through followed by the collapse of the edge beam.

Chief investigator Jean Berthier set out the basic findings of the team's report, expressed in its conclusions, at a press conference in Paris. explains these findings:

"The investigation identified two possible failure modes. Several external struts punctured the shell on the north side at the footbridge openings. Detailed calculations made during the inquiry indicate that some struts would have been overstressed. On the south side, the shell's edge beam fractured, falling off its bearings to the ground. Either of these mechanisms could have been the prime trigger.

But the report states that the concrete roof shell was inherently weak. The building was not designed to support the stress it was put under, and the concrete creep and fatigue caused by cyclical (irregular and intermittent) loading accelerated the failure. Finally, the introduction of connecting walkways into the side of the terminal created additional strain to the structure."