Friday, October 30, 2009
Florida has more vulnerable seacoast areas under construction than any other state, study shows -- South Florida Sun-Sentinel.com
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According to Technology News 10/21/2009:
Researchers at the Missouri University of Science and Technology have received $567,000 to explore how carbon fibers could improve the blast and impact resistance of conventional reinforced concrete.
According to Dr. Jeffrey Volz, professor of civil and architectural engineering, “The fibers will absorb more energy as they pull out during the pressure wave or impact, cutting down on the potential for failure during an explosion or earthquake, The fibers will also significantly diminish secondary fragmentation, reducing one of the leading causes of damage to surrounding personnel and materials.”
Fiber in concrete has been used for a very long time, primarily as a substitution for welded wire mesh on SOG and occasionally in structural elements.
Let’s not forget that one of the most important functions of fiber is to eliminate cracks due to shrinkage as water evaporates, increasing the tensile strength of concrete.
The reason that the size of fiber used in concrete is extremely small -- half of one inch in length, at max -- is the fact that fiber has the tendency to stick together and “ball up” when concrete is being mixed.
Researchers are very much aware of this characteristic. They intend to use fibers as long as 6 inches, and to identify a technology that permits the coating of the fiber particle, thus reducing the effect of coagulation or “balling up”.
Upon consideration, a serious question arises:
Is this research contemplating a possible elimination of conventional reinforcing, or, does it see it as a supplement to the conventional reinforcing, and, before spending over half of a million dollars, wouldn’t a feasibility cost study regarding the cost of coating the carbon fiber make sense?
Thursday, October 29, 2009
Are the bonding capacity and the contractual bonding provisions a strong deterrent for a contractor “Walk Off”?
Some may think that a substantial retainage to the contractor’s monthly requisition for payment is the answer. Others believe that a strong legal team working closely with the surety/insurance provider, would be the answer.
But it seems there is no clean cut solution to the problem, since the contractor, with initial honest and well-intended goals to complete the project, due to certain circumstances, is forced to declare bankruptcy or similar.
Fairness and openness at the time of contract negotiation between the Owner, Contractor, Surety Company, Insurance Company, Legal Teams, and Owner Consultants, may not be “The Complete Solution,” but it is most assuredly a step on the right direction.
And then. It's integral not to neglect the “Fairness Factor” when it relates to the actual construction of the project.
Monday, October 26, 2009
NXI, using patented manufacturing technology offers NX-SCR rebar, which features a carbon steel core, clad with a stainless-steel outer layer. This pairing provides equivalent corrosive resistance to solid stainless steel and equivalent mechanical properties to optimal Grade 60 (ASTM International Ratings).
It sounds like a great product, providing that adherence between the building core and cladding is obtained.
This technology has been previously tested by different manufacturers. The results were not very successful: a good bonding between the carbon steel core and the stainless-steel outer layer could not be obtained.
If NXI has achieved this bonding, their product must be of great interest when applied to infra structures, tunnels, atomic plants, sea walls and foundation for shore located buildings. Cost will be a factor that must be balanced with undeniable structural qualities.
In a conversation between Val Tuhari, of Construction Advisory Group, and Seth Fisher, NXI, VP, North America, it was revealed that the product must be imported from the U.K. until 2011 when their manufacturing facility will be completed here in the U.S. According to Seth, an average $5,000 per ton would be a fair number to consider and of course would depend on order magnitude.
The price may sound high. But, specific project considerations should balance the financial feasibility.
Monday, October 19, 2009
Building Design, 10/15/2009:
“Securing the design contract for the National Aquatics Centre for the Beijing 2008 Olympics was a task worthy of gold metal distinction in itself. Arup (a multinational engineering design, project management and consulting firm), and PTW (an architectural firm based in Sydney, Australia) beat out 10 qualifiers for this prestigious world-class project. Arup used MicroStation, MicroStation TriFormula, Bentley Structural and Bentley generative design technology for its unique design based on a natural pattern of organic cells and the formation of soap bubbles.”
This is an extraordinary revolution in structural design.
From Webster's, “Generative” is defined as , “having the power or function of generating, originating, producing or reproducing."
This sounds like the governing God’s laws, does it not? C
lassic structural design is based on clear and concise parameters related to mathematics and physic principles. This new approach exceeds those parameters.
Simply think about the “soap bubbles," smile and think again.
In essence, the optimal design for the “Water Cube” was determined by analyzing multiple configurations of thousand of steel members and connecting nodes.
We understand the concept started with The SmartGeometry Group that originated The London Gerkin Geometry. It is indeed revolutionary.
Thursday, October 15, 2009
The developer is Slazer Enterprises, the structural design by Cantor Seinuk, $200 plus millions and completion scheduled for the end of next year.
What is very interesting, is that it is almost a replica of Hugh Ferris’s futuristic drawings, dating from a century ago.
Wednesday, October 14, 2009
The five biggest percentage losses in construction employment over the year occurred in Arizona (27% or 50,000 jobs) and Nevada (25% or 29,500 jobs), followed by Connecticut, Kentucky and Tennessee.
Construction PPI (September 15, 2009) notes that the producer price index (PPI) for inputs to construction industries, a weighted average of the cost of all materials used in every type of construction, increased 1.1% in August compared to the previous month.
This increase was caused by a 17% increase in the cost of diesel fuel, a 6.8% jump in steel prices and a 11% rise in copper prices.
It must be time to get back to reality and common sense, which could include halting unnecessary changes in design standards and extricating politics from design and construction issues.
Tuesday, October 13, 2009
The projected savings are $108,000,000.
Here is the engineering beauty of the system. To build the temporary bracing structure, 60-foot steel columns (blue) were driven through the concrete-clad tunnel, then hung the tunnel from series of lateral steel I-beams (red and green) and suspension ties (yellow). (See the color-coded diagram for reference.)
Thursday, October 8, 2009
The Ocean Tower, considered to be the most luxurious tower in the region, a 31-story condominium project with 151 units, spa and other amenities, is structurally complete and in the interior finishing stage.
It is also sinking more rapidly than the attached parking garage structure, causing cracks in beams and columns.
Not intended to be an evaluation of this particular matter without knowledge of the design parameters, geotechnical conditions and applied geotechnical considerations/models, we do, however, have some input. In a tower structure with a garage attached, uneven settlements are always expected and design compensations as well as construction considerations are always provided. This is because the tower’s weight considerably exceeds the garage’s weight.
Most of us at the Construction Advisory Group have worked at the Marquis Tower, a Miami Florida project, for four years, from Preconstruction to Certificate of Occupancy. The Marquis Tower is a 67-story luxury condominium, with an attached garage, structurally similar to The Ocean Tower. As at most buildings located on beaches, the foundation system of The Marquis Tower consists of pile caps supported by friction piles/caissons. It is reasonable to assume that a similar system has been used at the Ocean Tower on South Padre Island.
On projects like this -- and because of expected differential settlements between the two structures -- the garage is built when the tower is close to completion (concrete) thus giving the necessary time for the sinking process to settle and the garage to be built on a more stable geotechnical condition. For example, at Marquis Project, we started erecting the garage when the tower was 40 stories high and when completed, the anticipated garage settlements matched with the respective elevations of the adjacent tower slabs.
Realizing that we do not know the actual field related provisions taken to prevent the Ocean Tower situation, it is a matter of speculation whether the same constructability approach was in use.
Saturday, October 3, 2009
"The plan calls for tax cuts, policy revisions, streamlined environmental reviews, increased government spending and other measures designed to spur the ailing construction economy, which has a 16.5 percent unemployment rate," the article continues.
This a a commendable action and worthy of applause from everyone with concerns and investments in the the construction arena. There are challenges, however, beginning with financial corruption, bureaucratic mismanagement and the general ongoing Federal Reserve Bank woes.
Challenges that are daunting, and may be insurmountable. Where does the industry go, good intentions in hand?