Is it Possible to Protect Homes from Damaging Tornados?

While architects are continuing to make strides in designing large commercial buildings that can provide more protection from natural disasters, the powerful EF4 and EF5 strength tornados that have occurred through parts of Alabama, Missouri, and Oklahoma over the last few years have demonstrated that single family, wood-framed homes offer little protection.  Not one of those styles of homes that were in the direct path of the forceful storms survived.  Moreover a recent report from Lloyd’s of London regarding the increasing risk of tornados finds that statistically the U.S. has more tornadoes than anywhere else in the world. 

Since many of the wood-frame structures destroyed by tornados were built with the most commonly used minimum standards of the International Residential Code, some people think the standards should be raised.  Though many experts that study the destruction of tornados think it is undesirable to try and build a fully tornado-proof home.  In order to be effective, it would have to be a windowless concrete bunker. 

There are some methods that can make your home more resistant to the damage from strong winds and flying debris that occurs during tornados.  A structural engineer from Simpson Strong-Tie, which makes high-strength metal connectors, suggested in an article from MSN that to resist strong winds, “Homes must be built with what is called a ‘continuous load path.”  The goal would be to create a “series of reinforced connections that tie every element together from roof to foundation, like a chain.”  

While this could be helpful in preventing some of the damage that might occur during a tornado, FEMA recommends that you do not try and tornado-proof your whole house.  Their suggestion is for those in highly prone areas to build a “safe room”.  These rooms can be a retrofitted closet or bathroom or a newly built space in your home and should effectively protect your family against the strongest wind forces.  A safe room does not need to be very large as tornados are over quickly.  They are typically built using reinforced concrete and compared to other ideas are a relatively inexpensive solution for a homeowner.  

Conco is one of the leading commercial concrete contractors in Sacramento and has been delivering first-rate services in the area since 1959.  We are experts at creating cost-effective solutions that take advantage of the most up-to-date techniques.  Our concrete services include commercial, educational, parking and other construction development as well as public works projects and highways.

Eighth Tallest Buildings in the World

Our eighth skyscraper in a series of blogs regarding the tallest buildings in the world is the Petronas Twin Towers in Kuala Lumpur, Malaysia.  The Towers became the tallest buildings in the world in 1998 by replacing Chicago's Willis (Sears) Tower until the Taipei 101 surpassed them in 2004.  They still retain the honor of being the tallest twin towers in the world. 

Architect on the project was Cesar Pelli & Associates who designed the postmodern building to create a distinct icon that promoted Kuala Lumpur as a commercial and cultural capital for the new millennium.  Planning on the Towers started in 1992 and the buildings were officially opened in August, 1999.  Engineer on the project was Thornton-Tomasetti Engineers and contractors were Mayjus and SKJ Joint Ventures.

Both of the Petronas Towers stand at 1,483 ft. and have a massive 10.7 million sq. ft. of space.  One of the most remarkably and well-known features of the skyscrapers is a dramatic two-​story bridge on the 41st and 42^nd floors that links the two buildings together.  It is the world’s highest double-decked bridge and is intended to symbolize a gateway to the future and provide stunning views of Kuala Lumpur.

According to the Petronas website, the building of the Towers required the single largest and longest concrete pour in Malaysian history.  It took 13,200 cubic meters of concrete that was continuously poured over 54 hours for each of the towers.  By the end of the pours, each Tower had a record-breaking slab with 104 piles that formed the foundation.  

 

 Conco is a leading supplier of concrete services for the Western United States and is once again involved in doing concrete work for a major landmark project. The new Wilshire Grand Center will reshape the Los Angeles skyline as the tallest building west of the Mississippi.  As a part of the project, Conco successfully poured the largest continuous mat foundation ever done in the U.S. on February 15, 2014.

 

 

 

 

 

 

 

Using Tower Cranes to Build Skyscrapers

In order to build the super tall skyscrapers of today such as the Wilshire Grand Center in Los Angeles, huge tower cranes are used.  Tower cranes are capable of lifting very heavy loads of steel, concrete, generators and other building materials and can be erected to grow taller as the construction project moves upward.   

Before a tower crane is ready to use, it needs to be stabilized at the jobsite.  The process entails building a concrete pad with large anchor bolts embedded into the concrete that secures the base of the crane.  Once a tower crane reaches its maximum height, it can be tied to the side of the structure with steel collars and moved upward as a project demands.

The gears and motor for the crane are contained in the slewing unit that is attached to the mast and which allows the crane to rotate.  On top of that is the long jib that is used to lift the heavy materials as well as the counter-jib that works as a counter-weight to keep the crane balanced.  The crane operator may control the unit from the ground or in a cab that is on top of the tower.

The tower crane mast is a steel triangular lattice structure that is constructed of vertebras generally 10 square feet in size.  Once a crane has been fastened to the exterior of the building or in some cases to the interior and needs to be raised higher, the process is started to add new pieces.  A climbing frame or metal sheath that sits between the slewing unit and the top of the tower is used to temporarily support that section of the mast while the jib moves a new segment into the space.  Once the new piece is bolted down, the climbing tower then moves higher up along the mast ready for the process to begin again. 

According to Wikipedia, typically the maximum unsupported height of a tower crane is 265 feet and the maximum reach of the jib is 230 feet.  It has a maximum lifting strength of 19.8 tons.  

 

Conco’s team of professional concrete contractors in the Portland area brings the highest level of integrity and principles to each project from pre-construction to finish.  With the rapidly growing construction market, Conco is taking an active role in the Portland area with our expansion of high-quality commercial concrete services.

Retrofitting Historic Buildings Against Earthquakes

New construction is being built better than ever to withstand the threat of earthquakes.  Moreover since earthquake activity is not limited to the West Coast, local building codes throughout the country mandate that new construction be resistant to the strongest earthquake activity that is believed possible in an area.  This task has become easier with new high-tech materials that are available such as fiber-reinforced polymers, fiber reinforced concrete and high strength steel.  

One of the on-going phases in creating safer buildings is the seismic retrofitting of older structures to be more resistant to seismic activity and ground motion.  Among these projects include significant historical buildings that have the additional task of ensuring the structure is stronger while still preserving the distinctive characteristics that make the buildings special.  

Obviously first and foremost human safety is addressed and then the focus switches to work on retaining the distinct architectural features of the building. Common weaknesses in historic buildings when faced with earthquake activity include unreinforced masonry and structural connections between walls, floors, and foundations.  Older construction used unreinforced bearing walls that offer inadequate lateral resistance and ductility or flexibility when subjected to seismic activity.     

According to the NPS Department of Interior’s Preservation Briefs, it is imperative to put together a team of experienced engineers, architects, and building code officials as well as consulting with their agency’s administrative staff.  They state that, “Historic materials should be preserved and retained to the greatest extent possible.”  Also that, “New seismic retrofit systems, whether hidden or exposed, should respect the character and integrity of the historic building and be visually compatible with it in design; and that, seismic work should be ‘reversible’ to the greatest extent possible to allow removal for future use of improved systems and traditional repair of remaining historic materials.” 



 

Conco is a leading supplier of concrete services for the Western United States. We have built our reputation in the Los Angeles area with superior concrete formwork, reinforcing, place and finish, shotcrete and other ancillary services that benefit from our vast experience.  Our concrete services include commercial, educational, parking and other construction development as well as public works projects.

 

Seventh Tallest in the World - International Commerce Centre

While we are currently providing concrete services for the new Wilshire Grand Center in Los Angeles, which is on its way to becoming the tallest building in the U.S. west of the Mississippi, we have started blogging about other tall skyscrapers.  We recently saw an article from the Council on Tall Buildings and Urban Habitat that is already discussing the emergence of mega tall skyscrapers that will be built in the next decade.  Apparently a kilometer-tall (3280 ft.) building is already under construction.  The CTBUH now defines super tall skyscrapers as those over 300 meters (984 ft.) and buildings over 600 meters (1968 ft.) as mega tall.    

On our list of buildings, we are at number seven, which is the International Commerce Centre in West Kowloon, Hong Kong.  The 1,588 ft. building has 118 floors with a 360 degree observation deck and is the tallest building in Hong Kong as well containing the third largest number of floors.  The ICC was completed in 2010 and a winning entry in an international design competition.  The project was designed by the American architectural firm Kohn Pedersen Fox Associates (KPF) in association with Wong & Ouyang (HK) Ltd.

The skyscraper is part of the Union Square reclamation project and is built right above the Kowloon Station, which connects Hong Kong to the airport.  According to ArchDaily, the structure is made up of eight concrete mega-columns that “splay out 3 degrees as they touch the ground plane.”  The building includes office, retail, a hotel and the world’s highest cocktail lounge on the 108^th floor.   

Energy efficient abounds in the skyscraper and set new standards for sustainability.  It contains an “Energy Optimizer” air-conditioning system and a passenger smart elevator system that maximizes efficiency by assigning elevators to groups with similar destinations.  Water is saved by harvesting water from the a/c system and used in cooling towers and other situations that use non-potable water.      

Conco is a leading supplier of concrete services for the Western United States and is once again involved in doing concrete work for a major landmark project. The new Wilshire Grand Center will reshape the Los Angeles skyline as the tallest building west of the Mississippi.  As a part of the project, Conco successfully poured the largest continuous mat foundation ever done in the U.S. on February 15, 2014.

Bellevue, WA has consistently been rated as one of the top places in the country to live, work, and to raise a family.  The vibrant community offers a first-class school district, a wide-range of outdoor activities, and entertainment venues as well as great restaurants and retails stores.
Conco was pleased to provide concrete services for the Washington Square high-rise condominium project.  It was the first stage of a large development complex that is being built in the heart of downtown Bellevue.  The two 22-story condo towers were completed in 2008 and have a total of 377 residential units.  Built as a model of urban living, the development boasts an attractively landscaped courtyard, tree-lined walkways, and a convenient dog park.  Amenities include concierge services, night doorman, spa, massage rooms, and a fitness center

Fifth Tallest Building in the World - Taipei 101

Since starting work on the Wilshire Grand Center in Los Angeles, which is set to become the tallest building in the U.S. west of the Mississippi, we started a series exploring the super tall skyscrapers of the world.  As we proceed along in the series, we now arrived at the fifth tallest building in the world.  The Taipei 101, also known as the Taipei Financial Center, is located in the Hsinyi district, Taipei, Taiwan.

Recently replaced as the tallest building in Asia by the Shanghai Towers that is currently being constructed, the Taipei 101 was opened in 2004 and stands at 1,671 ft. tall.  The building has 101 floors with an indoor observatory deck at that level.  The steel and glass skyscraper was designed by C. Y. Lee & Partners and the structural engineers were Thornton Tomasetti and Evergreen Engineering.  The Project Manager was Turner Construction.  The building was awarded the highest LEED Platinum certification.

According to an article from Wikipedia, the Taipei was constructed to withstand adverse conditions that have been known to occur in the area such as typhoon strength winds or earthquakes.  The ultimate goal was to construct “a structure that could withstand gale winds of 134 mph and the strongest earthquakes likely to occur in a 2,500 year cycle.”  Using very strong reinforced concrete supports and an extremely solid foundation, the Taipei 101 is believed to be one of the most stable buildings ever constructed.  

The multi-use skyscraper has retail shops on the first four levels, a large fitness center on floors 5 and 6, and offices space above that on levels 7- 84.  A variety of fine restaurants can be found on floors 86 to 88 and outdoor observation decks on level 89 and 91. 

Conco is a leading supplier of concrete services for the Western United States and is once again involved in doing concrete work for a major landmark project. The new Wilshire Grand Center will reshape the Los Angeles skyline as the tallest building west of the Mississippi.  As a part of the project, Conco successfully poured the largest continuous mat foundation ever done in the U.S. on February 15, 2014.