The environment changes… and construction? (Part 2)

The precast/prestressed concrete structures industry has always been haunted by the ghosts of false beliefs that surround it. A few weeks ago, in part 1 of this article, we pointed out some of them: that the project be "square," that prefabricated projects are good but more expensive, the adequate structural behavior cannot be guaranteed in earthquakes, it is only applicable in large construction projects and the technology is not yet developed in our country.

Over the last 25 years or perhaps more, Mexican companies have gathered together, unionized, have spread their construction systems, won contracts and raised copies that have proven to be competitive in price, fast in construction and excellent in behavior in high-intensity earthquakes, leaving behind the myths and beliefs that for many years defined them. 
 

This time, we will discuss the current advantages that these systems provide to the real estate investment projects in which they participate.

Excellent Adaptability 

We would tire the reader if we listed all the  examples of projects resolved with prefabricated elements that are demanding in terms of architectural design and sophisticated in form, such as football stadiums, residential towers, hotels and shopping centers, and in which the line drawn by the design represents its own personality. So despite it seeming that only straight lines canbe achieved by prefabrication, the ingenuity, creativity and above all the versatility of these systems have managed to satisfy tremendous expectations and even more have surpassed and exceeded said demands and challenges.

Record Construction Times

Adequate and timely planning, attention to detail in the project stages and participation and commitment from the perspective architecture, structure and construction (in the plant and at the construction site) from the beginning of the project leads to the expected results. I have always established that the prefabricators are not the "supermen" of construction but simply plan and thus manage to reduce the work programs by initiating activities in the plant, independently and simultaneously with the progress of activities on the construction site. That is precisely the detail that eliminates chains of activities having precedence over one another. For example, the casting of columns and stories in the fabrication location can be started even when earthwork, excavations and foundations are just being carried out at the construction site. In this way, we change the phrases "wood forms, reinforcing steel and concrete cast" for a single one called "mounting."
 

Competitive Costs,Better Returns 

Is it possible to achieve the benefits, such as rapid construction, quality of work, durability, greater free spaces without columns, thermal and acoustic insulation and additional LEED points,  without paying more and also with a better T.I.R.? Yes, it is possible. These are achieved through prefabrication when the aforementioned is put into practice. A good project is the sum of architecture plus structural engineering plus the construction system. If any of the three  does not attend the appointment or arrives alone, the result will be mediocre and without benefits. The three must participate from the beginning and without fear. Comparative analyses are the basis for a good choice of system and this is the basis for the success of the project. Good architecture will always be the key; it is like thinking that an airplane (the project) flies quickly because it has an aerodynamic fuselage, wings and powerful turbines. The structural engineering is very modestly just the landing gear on that aircraft, but it is incredibly important. Without it there is no way for the plane to fly safely. The construction system could be the materials, the screws, the aluminum, the assemblies, the good execution. All of them together, working in coordination, make the plane fly at supersonic speeds, transporting hundreds of passengers and many tons of cargo with absolute safety. 

Total Structural Safety 

Structural safety protects human lives above all but also property assets. All efforts to improve related features and time and cost benefits would not be justified if there were not 100 percent structural safety. Prefabricated structures have been identified as "risky" due to their allegedly low ductility. Therefore, the seismic codes of many regions of the world punish them with seismic design forces up to 100 percent greater than those used in all other construction systems, such as steel and cast-in-situ. However, in the most recent studies carried out by the Instituto de Ingeniería of the National University of Mexico (II UNAM) and the National Disaster Center (CENAPRED), it has been shown that the connections between prefabricated pieces are capable of resisting great force, adequately releasing the energy of the earthquake and with very adequate hysteretic cycles, even better than those achieved by traditional systems. It is the intention of the prefabricator guild to at least remove or go through the curtain of the "veto" to these these systems and then standardize the design forces, thus making them much more competitive. 
 

In conclusion, we should open our minds, remove bias, plan ahead, and execute cleanly. No one is a better ally of architecture than the prefabricated. No one is a better ally of construction than precast and no one is a better ally of precast than good and timely planning.