All of Puerto Vallarta has the same seismic zone and developers have the option of designing their structures based on the official seismic design manual for Mexico and the required minimum criteria for each seismic zone, or alternatively, doing an independent investigative study specific to the site to formulate a minimum criteria. HEVA always makes a site specific investigation prior to any design. For an example, a standard building would contain 70 kg of steel per CM of concrete, a very strong building contains 100kg of steel per CM of concrete, HEVA'S design at V Conchas Chinas consists of 155 kg of steel per CM of concrete. (We have 427 metric tons of steel and 2750 CM of concrete in the structure!) Our engineers design the components of the structure individually, some with more than double the required criteria, based on their experience, the project specific study and HEVA's request. Additionally, we perform a deep excavation and as result the project sits on solid rock.
Why HEVA chooses CONCRETE VS STEEL:
Both concrete and steel, when designed and built correctly, perform equally well in seismic situations, and both have pros and cons to consider when preparing a design. HEVA considered both steel and concrete carefully, and have used primarily concrete in our structures in Puerto Vallarta because we are certain it is the best long-term option for our clients, for the following reasons:
• The biggest threat to steel is corrosion of both the steel components and their connection points, (bolts, rivets and welds). The steel is shipped with a primer coat of paint, but during shipping and erection the steel gets badly scratched and exposes the steel to corrosion, as a result the structure needs to be primed and painted to have proper protection against corrosion. Additionally, every connection weld, bolt or rivet needs primer and paint after installation, and professional inspection and testing. Even if all of these steps are followed, paint has a life expectancy that is questionable in normal climates, in a tropical salt air climate HEVA's opinion is that paint is not adequate protection and steel structures are a recipe for constant maintenance issues. The life of a steel structure will depend on the consistency and attention to maintenance that it receives.
• Concrete does not have any of the corrosion problems of steel, is much less problematic in terms of construction, and requires NO ongoing maintenance. HEVA pours test cylinders from every truck of concrete and does compression tests of each truck at 7, 14 and 28 days, to confirm compressive strength, plus HEVA takes temperature readings of every truck of concrete to insure it is within range for proper placement before pouring. These advantages combined with the fact that HEVA employs engineers as supervisory staff for the construction, ensure our structures will outlast steel structures in this tropical salt air environment many times over, and beyond all our lifetimes.
• Steel structures are noisier than concrete structures. The steel structure floors are covered with steel pan deck; which is filled with concrete, typically 15 – 20 cm in thickness, when impact noise is subjected to the flooring it can transmit through the structural members to other parts of the building. There are sound isolation products to reduce the problem, but HEVA's opinion is that sound transmission between units is paramount to our clients’ needs, and concrete performs better. By comparison the floors at V Conchas Chinas are 40 cm thick, with structural NOVIDESA components that provide a virtual soundproof separation between units. You will not hear steps or audio noise between floors.
• Steel structures in the US and Canada require a special fireproofing product to protect the steel structure in case of fire. That fireproofing material is not normally used in Mexico, leaving the steel structure vulnerable to severe damage in the event there was a serious fire. HEVA was not comfortable with this risk.