The performance building code
How did lightweight high-rise construction evolve since WWII? It evolved with the help of the so-called performance code. After WWII the builders complained about building codes. They said they were too restrictive and specified every detail of construction. They called the old building codes “specification codes”. They complained the codes specified the size and type and some times even the make of a product used in construction. They decried the specification code as old fashion. They wanted the building codes changed to what they called “performance codes.” They wanted the building codes to specify the performance requirements only; and, not specify the size and type of building material to use. For example, with fire resistive requirements they wanted the code to state just the hours of fire resistance (one, two, three or four hours) required by law; and not to state the specific type and material used to protect structural steel and enclosures for stairways and elevators shafts. For example, a performance building code states: the steel has to be protected against heat of flames for one, two, three or four hours during a fire. It does not state what to use as a fire resisting material. This performance code signaled the end to concrete encasement fire protection and allowed a spray on fire protection for steel and plasterboard enclosed stairs and elevator shafts. Builders hailed the New York City building code of 1968 as a good performance code. However, some fire chiefs decried it as a law that substituted frills for real construction safety. The asbestos spray on coating of steel trusses used in the WTC towers was considered by Chief of the New York City Fire Department, at the time, John T. O’ Hagan to be inferior to concrete encasement of steel. Writing in his book, High Rise Fire and Life Safety. l976, he listed the following problems of spray-on fire protection of steel:

Failure to prepare the steel for spray-on coating adhesion. Rust and dirt allowed spray-on fire retarding coating to scale and fall away from steel during construction
Poor or uneven application of the spray-on fire retarding was discovered during post fire investigations
Variation of spray-on material during manufacture makes it ineffective
Lack of thoroughness in covering the steel during application is a problem
Failure to replace spray-on material dislodged by other trades people performing work around the steel during the construction of the building.
The WTC started construction in the 1970s. And the WTC towers built by the Port Authority of New York did not have to comply with the minimum requirements of the new1968 performance building code.

Recommendations for constructing the new high rise buildings on ground zero
The steel columns, girders and floor beams should be encased in masonry or other more effective fire retarding material. Spray-on fire retarding is ineffective. Post fire investigations reveals the spray on fire retardant has scaled off and steel beams and concrete and steel floor slabs crack and allow flame spread.


Lightweight bar joists should not be used to support floors in high-rise buildings. The National Fire Protection Association has shown unprotected steel bar joist fail after five or ten minutes of fire exposure.


For life safety in high-rise buildings bring back the smoke proof tower. This allows people to escape fire using smoke free stairways.


Stairs and elevator shaft ways should be enclosed in masonry to prevent smoke spread.


Heating ventilation and air condition HVAC systems should be provided by unit system serving only one or two floors. Central air system serving 10 or 20 floors creates shaft ways and duct systems that penetrate fire rated floors walls partitions and ceilings. Smoke spreads throughout ducts of central HVAC systems.
The high rise building framework should be skeleton steel framing not center core steel column framing. There should be no bearing wall high rise construction. Reduce the size of open floor design.
Increase the thickness of concrete in floor construction. The two or three inches of concrete over corrugated steel fails during most serious high rise fires and must be replaced.
Automatic sprinklers should protect all high rise buildings. Firefighters can extinguish approximately 2,500 square foot of fire with one hose line. Two hose steams may quench 5,000 square feet of fire. The World Trade Center floor areas were 40,000 square feet in area.
Federal, State and Port Authority buildings should comply with New York City building codes and actually in some cases should exceed them. Remember building codes are only minimum standards.

Engineering Society Accused of Covering Up Design Flaws in Investigations of Katrina, World Trade Center

NEW ORLEANS — The professional organization for engineers who build the nation's roads, dams and bridges has been accused by fellow engineers of covering up catastrophic design flaws while investigating national disasters.

After the 2001 attack on the World Trade Center and the levee failures caused by Hurricane Katrina in 2005, the federal government paid the American Society of Civil Engineers to investigate what went wrong.

Critics now accuse the group of covering up engineering mistakes, downplaying the need to alter building standards, and using the investigations to protect engineers and government agencies from lawsuits.

Similar accusations arose after both disasters, but the most recent allegations have pressured the organization to convene an independent panel to investigate.

"They want to make sure that they do things the right way and that they learn lessons from the studies they do," said Sherwood Boelhert, a retired Republican congressman from New York who heads the panel. He led the House Science Committee for six years.

The panel is expected to issue a report by the end of April and may recommend that the society stop taking money from government agencies for disaster investigations.

The engineering group says it takes the allegations seriously, but it has declined to comment until completion of the panel's report and an internal ethics review.

In the World Trade Center case, critics contend the engineering society wrongly concluded skyscrapers cannot withstand getting hit by airplanes. In the hurricane investigation, it was accused of suggesting that the power of the storm was as big a problem as the poorly designed levees.

The group has about 140,000 members and is based in Reston, Va. It sets engineering standards and codes and publishes technical books and a glossy magazine. Members testify regularly before Congress and issue an annual report on the state of the nation's public-works projects.

The society got a $1.1 million grant from the Army Corps of Engineers to study the levee failures. Similarly, the Federal Emergency Management Agency paid the group about $257,000 to investigate the World Trade Center collapse.

The engineers were not involved in investigating last year's bridge collapse in Minneapolis.

The society issued a report last year that blamed the levee failures on poor design and the Corps' use of incorrect engineering data.

Raymond Seed, a levee expert at the University of California, Berkeley, was among the first to question the society's involvement. He was on a team funded by the National Science Foundation to study the New Orleans flood.

Seed accused the engineering society and the Army Corps of collusion, writing an Oct. 20 letter alleging that the two organizations worked together "to promulgate misleading studies and statements, to subvert appropriate independent investigations ... to literally attempt to change some of the critical apparent answers regarding lessons to be learned."

Maj. Gen. Don Riley, the corps' director of civil works, disputed Seed's allegations at a December meeting in New Orleans.

"He talks about the supposed cover-up," Riley said. "Well, our people live here in New Orleans ... We don't stand behind our work. We live behind our work."

In 2002, the society's report on the World Trade Center praised the buildings for remaining standing long enough to allow tens thousands of people to flee.

But, the report said, skyscrapers are not typically designed to withstand airplane impacts. Instead of hardening buildings against such impacts, it recommended improving aviation security and fire protection.

Abolhassan Astaneh-Asl, a structural engineer and forensics expert, contends his computer simulations disprove the society's findings that skyscrapers could not be designed to withstand the impact of a jetliner.

Astaneh-Asl, who received money from the National Science Foundation to investigate the collapse, insisted most New York skyscrapers built with traditional designs would survive such an impact and prevent the kind of fires that brought down the twin towers.

He also questioned the makeup of the society's investigation team. On the team were the wife of the trade center's structural engineer and a representative of the buildings' original design team.

"I call this moral corruption," said Astaneh-Asl, who is on the faculty at the University of California, Berkeley.

Gene Corley, a forensics expert and team leader on the society's report, said employing people with ties to the original builders was necessary because they had access to information that was difficult to get any other way.

Corley said the society's study was peer-reviewed and its credibility was upheld by follow-up studies, including one by the National Institute of Standards and Technology.

"I hope someone looks into the people making the accusations," Corley said. "That's a sordid tale."