Advanced tech and a fresh approach is helping construction firms 'go lean'
Challenges are forecasted for the construction industry in 2015, but they are different from the trials industry leaders faced in recent years. After a difficult start to 2014, the industry is recovering, adapting to new regulations and techniques, contending with labor and material shortages and implementing advanced technology. These factors create risk and potential setbacks, as well as tremendous opportunity for greater success in the new year.
The United States economy has continued to gain momentum, but the construction industry still dealt with the hangover from the downturn in 2014. The first six months of 2014 provided few new building opportunities. This was coupled with additional regulations, including healthcare reform and labor reporting, causing more hurdles for businesses. The sluggish market and time required to adapt to new guidelines bred an overall environment of cautious advancement. The turn came in mid-2014 as the market surged with a year’s worth of opportunities to be completed in just months. While the increase in work in 2014 was welcomed, those new regulations and requirements created unexpected extra costs that extend into 2015.
Those increased costs are just one issue that carries into this year as the industry works its way back from the recession. Companies continued to downsize last year, either through attrition or continued layoffs. The decrease in available workers could make it more difficult for companies to keep up with demand, which make joint ventures a likely path forward in the near-term. Companies will team up to handle the increasing demand, and owners may return to selecting a project team on a best value, rather than least expensive, basis.
While joint ventures allow for progress and probable industry growth, the labor-shortage problem is not going away. Even with a steady increase in demand, the industry probably won’t see a rise in labor. To begin to solve this dilemma, technical schools are working to revive and redesign their programs to attract a new generation of students to the construction field. In addition to improving education programs, passing comprehensive immigration reform will increase the labor pool and have an immediate, positive impact in construction. However, both of these measures will likely be a several year process, which means that the industry must rely on other measures, such as new building techniques and industry-wide collaboration, to continue its forward momentum.
Experimenting with new building techniques is always an evolving process, but it also provides a method to help address the labor shortage. Traditional practices involve bringing materials to the job site to erect a building. This takes time and is expensive compared to prefabrication techniques. Prefabrication is just what it sounds like: assembling a structure in a warehouse or other manufacturing site, transporting completed sections of structure to the site and putting those sections together to create the final structure. Long used in the housing industry, the practice is finding inroads in the commercial and industrial spaces as well. The approach allows businesses to take into account conditions of materials, natural elements, budget and labor, as well as providing a means of fixing issues more quickly than when building on site. Prefabrication techniques are advancing quickly due to technology improvements, which aid in reducing costs and completing builds with less labor.
Co-construction is another technique industry leaders are using to help combat labor shortages and limited resources. Co-construction is essentially allowing one team to build upon another’s work to collaboratively complete a project. While more companies are creating these teaming agreements, there is some risk involved. Co-construction leaves room for error and miscommunication. Effective co-construction incorporates sharing accountability in a fair and reasonable manner, while not creating an undue burden on the owner. Still, the practice has the potential to better serve and benefit owners as well as the teaming companies delivering the project.
Technology advancements help mitigate risks associated with co-construction as well as provide a platform for the industry’s early adopters to effectively progress in the coming year. Companies are implementing those technologies that allows for faster construction processes and more efficient use of the limited labor pool. Although some industry leaders are less comfortable with the ever-changing technology, the need for faster, more efficient techniques will likely outweigh, or at least lessen, any reluctance.
The construction industry is at an exciting turning point right now. We’ve collectively weathered the worst of the storm and see a bright path forward to create new industry standards for the coming year and beyond. In many ways, the downturn has forced the industry to reexamine its practices, technologies and overall approach to delivering projects. The opportunity for increased efficiency due to co-construction, prefabrication and advanced technology is great, but success will depend, in part, upon the open-mindedness of industry leaders and the incorporation of multigenerational ideas of how to improve the construction process.
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.