Top 5 US construction projects in 2015
Although the construction industry has seen some rough patches the past decade, commercial construction projects in the US are steadily increasing.
From high rises to highways and every commercial project in between, large-scale construction is seeing a resurgence all across the country.
Here are a few commercial construction hotspots in the United States:
States with most commercial construction
As US cities continue to expand, commercial construction is keeping up with growing infrastructures. Although cities like Tampa, Baltimore, and San Jose are experiencing a boom in commercial construction with billions of dollars in future projects, there are other US cities that take the construction cake.
According to United States Census Bureau's Metropolitan Statistical Areas, commercial construction projects in New York, N.Y. exceeded the $20 billion mark in 2014 alone. Tied for second place are Dallas and Houston with $11.1 billion in commercial construction projects. Other notable cities are Los Angeles and Miami, which both exceeded the $6 billion mark in commercial construction projects.
Infrastructure projects are rapidly growing in metropolitan areas across the United States. For example, O'Hare International Airport is getting an $8.8 billion facelift in order to better serve the 65 million passengers that fly through the airport each year. The Dulles International Airport in Washington, D.C. is getting a similar facelift and a new 20-mile transit system to the tune of $6.2 billion.
As for roadways, the Volkert engineering firm signs on for $2.3 billion highway project that is aimed to alleviate traffic on the Interstate 4 stretch between Orlando and Tampa.
The commercial construction project will cover 21 miles of interstate and take an estimated 6.5 years to complete.
The airport projects above are receiving funding on the federal level as well as using funds from passenger fees. The Florida interstate project is mostly relying on federal grants as well as funding from the state's toll system.
Future interstate construction
The United States is covered with highways, byways, and interstates.
As populations continue to increase, so does the need for more interstates. There are currently two major interstate additions planned for the future: Interstate 11 and Interstate 41.
Instate 11 will run through Tucson and Phoenix, Arizona and end in Las Vegas, Nevada, which is nearly 300 miles of roadway. Interstate 41 will run 175 miles from Russell, Illinois to Green Bay, Wisconsin. Both of these massive projects are sure to keep commercial contractors busy for years to come.
Other interstate proposals include routes in the Southeast, Midwest, and Northeast totaling hundreds of miles in new interstate. Although these proposals haven't been set in motion yet - when they are - commercial infrastructure projects in the US will likely skyrocket.
From state to state and city to city, commercial construction is helping to improve the country's infrastructures. With private companies concentrating in the construction of office buildings and high rises, these structures are changing cityscapes for the better.
Government contractors are completing overpasses and interstate additions at impressive rates.
These government infrastructure projects are helping to support other private sector commercial construction projects by making it easier to access and commute to growing metropolitan areas.
When it comes to commercial construction, the US is expanding by leaps and bounds.
Adam Groff is a freelance writer and creator of content. He writes on a variety of topics including U.S. and global construction.
Why engineers must always consider human-induced vibration
Human induced vibration, or more accurately vibrations caused by human footfall, often conjures images of Millennium Bridge-style swaying or collapsing buildings.
But in reality, the ‘damage’ caused by human-induced vibrations is less likely to ruin a structure and more likely to cause discomfort in people. Though not as dramatic as a structural failure, any good engineer wants to make sure the people using their structures, be it bridges or buildings or anything in between, can do so safely and comfortably. This is why human-induced vibration must be considered within the design process.
Resonance v Impulse
There are two ways that human-induced vibrations affect structures: resonant, and impulse or transient response. Put simply, resonance occurs when Object A vibrates at the same natural frequency as Object B.
Object B resonates and begins to vibrate too. Think singing to break a wine glass! Although the person singing isn’t touching the glass, the vibrations of their voice are resonating with the glass’s natural frequency, causing this vibration to get stronger and stronger and eventually, break the glass. In the case of a structure, resonance occurs when the pedestrian’s feet land in time with the vibration.
On the other hand, impulse or transient vibration responses can be a problem on structures where its natural frequencies are too high for resonance to occur, such as where the structure is light or stiff. Here the discomfort is caused by the initial “bounce” of the structure caused by the footstep and is a concern on light or stiff structures.
Engineers must, of course, design to reduce the vibration effects caused by either impulse or resonance.
Potential impacts from human induced vibration
Human induced vibration can lead to a number of effects upon the structure and its users. These include:
- Interfering with sensitive equipment Depending on the building’s purpose, what it houses can be affected by the vibrations of people using the building. Universities and laboratories, for example, may have sensitive equipment whose accuracy and performance could be damaged by vibrations. Even in ordinary offices the footfall vibration can wobble computer screens, upsetting the workers.
- Swaying bridges One of the most famous examples of human-induced resonance impacting a structure occurred with the Millennium Bridge. As people walked across the bridge, the footsteps caused the bridge to sway, and everybody had to walk in time with the sway because it was difficult not to. Thankfully, this feedback can only occur with horizontal vibrations so building floors are safe from it, but footbridges need careful checking to prevent it.
- Human discomfort According to research, vibrations in buildings and structures can cause depression and even motion sickness in inhabitants. Tall buildings sway in the wind and footsteps can be felt, even subconsciously by the occupants. It has been argued that modern efficient designs featuring thinner floor slabs and wider spacing in column design mean that these new builds are not as effective at dampening vibrations as older buildings are.
- Jeopardising structural integrity The build-up of constant vibrations on a structure can, eventually, lead to structural integrity being compromised. A worse-case scenario would be the complete collapse of the structure and is the reason some bridges insist that marching troops break step before crossing. Crowds jumping in time to music or in response to a goal in a stadium are also dynamic loads that might damage an under-designed structure.
How to avoid it
As mentioned, modern designs that favour thinner slabs and wider column spacing are particularly susceptible to all forms of vibration, human-induced or otherwise, but short spans can also suffer due to their low mass. Using sophisticated structural engineering software is an effective method for engineers to test for and mitigate footfall and other vibrations at the design stage.