Update on the Wilshire Grand Tower in L.A.

In order to open on schedule in early 2017, the new Wilshire Grand tower in downtown Los Angeles has been on an accelerated timetable from the start, which also includes the concrete services that are The Conco Companies’ responsibility.  After successfully breaking the world record for the largest continuous mat pour this past February, Conco is working to provide the rest of the concrete work on the new skyscraper.   

The ambitious project calls for a poured-in-place core wall going up the building that is surrounded by slab on metal deck.  The core of the tower will be 130 ft. X 35 ft. with some floors having walls up to 4 ft. thick.  Conco is on a 4-day core wall cycle, which means that every 4 days; concrete for a new floor is poured. 

The Wilshire Grand was designed by AC Martin Architects and the contractor on the project is the Turner Construction Co., one of the largest general contractors in the U.S.  The 1,100 ft. tall skyscraper will become the tallest building in the West upon completion, and as a result, is a complicated engineering project.  The tower had to be designed to sway during powerful Santa Ana winds, and also absorb ground movement from the strongest earthquakes. 

Furthermore the project is designed with green technology inside the building as well as the exterior.  It started with the “green deconstructing” of the old Wilshire Grand Hotel on the site in the fall of 2012.  Rather than imploding or demolishing it, the process enabled much of the old building materials to be recycled.  The combined steel and concrete that was recycled brought close to $4 million in revenue that was put back into the project. 

Highly energy efficient climate systems and innovative lighting will be used throughout the building.  With the addition of the green building techniques and material, the Wilshire Grand is on track to receive LEED Silver certification.   

Sources:

latimes.com/local/la-me-wilshire-grand-foundation-20140426-dto-htmlstory.html   

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.  We have been offering premium concrete services throughout the Western U.S. since 1959, and have four regional offices serving California, Washington, Oregon, Nevada and Colorado.

Why Concrete Shrinks and How it is Addressed

All concrete experiences some degree of shrinkage, which can result in cracks in the concrete.  Shrinkage may also affect the long-term strength and durability of the concrete.  Even though concrete contractors know that shrinkage is caused by a loss of volume that occurs in different stages of the process, it is still challenging to prevent or alleviate shrinkage, and thereby the cracking.  It is especially an important consideration when constructing industrial floors or pavement.

Since shrinking is one of the inherent properties of concrete, it is impossible to totally eliminate cracking but it can be controlled.  This is why contractors and engineers work to understand and address the volume change in concrete to reduce the amount of shrinkage.

According to the Portland Cement Association, “The shortening of concrete slabs can be caused by temperature decreases or moisture loss. These two causes are also related to curling and warping of slabs, respectively. Curling is the deformation of the slab due to a difference in temperature between the surface and the bottom of the slab (temperature gradient).  Slab “warping” is the deformation of the slab surface profile due to a difference in moisture between the surface and bottom of the slab (moisture gradient).”* 

To quickly move and place concrete, it is mixed with more water than is absolutely necessary for hydrating the cement materials.  Once the concrete is placed, the excess water separates from the hardening concrete, which results in a loss of volume that causes the concrete to shrink.  The concrete’s reinforcement or base friction works to restrain it, which in turn can create tensile stresses in the slab causing cracks. 

In an effort to prevent the shrinkage, one of the things that contractors watch out for is fluctuating temperatures during the first 24 hours after placement.  Also considerable care is taken to use the correct concrete mixture design so that the least amount of extra water is added and the largest size of aggregate is used.  All of this works toward reducing shrinkage.

*http://www.cement.org/for-concrete-books-learning/concrete-technology/focus-on-floors/concrete-shrinkage

 

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.

 

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.

The Earliest Cranes

A crane is a type of machine that creates a mechanical advantage for moving heavy objects that are beyond the normal capacity of a man.  It can lift and lower objects and move them horizontally to transports heavy materials from one place to another using a hoist or winder, wire chains, and sheaves (wheels or rollers).  A crane is an essential piece of equipment in the construction industry, the transportation industry, and the manufacturing industry.

The invention of the crane has had important implications on the advancement of our civilization.  It is thought that the most powerful hand crane in history could multiply the force it imparted to the operator by 632 times.  When looking at what the Egyptians accomplished with the building of the Pyramid, 50 men were utilized to move a 2.5 ton stone block, which translates to about 50 kg per person.  During the Roman Empire, a Roman crane increased the lifting capacity of a person to about 3,000 kg or 60% higher. 

Historians believe that the Ancient Greeks were the first to invent cranes in the late 600 BC and were powered by men or animals.  Archeologists have discovered distinctive cutting marks on stones from early Greek temples that prove they were lifted by cranes.  These early cranes were made of wood and enabled the Greeks to construct taller buildings. 

The Romans further advanced the development of the crane that allowed for larger and heavier weights to be lifted.  They invented cranes that were powered by groups of men or animals and used extensive pulley and rope systems.  The Roman Polyspastos crane consisted of 3 ropes and 5 pulleys which were worked by 4 men to move 3,000 kg.  

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.