Concrete Construction Methodology
Concrete is an all-round construction material. Typical Maltese construction relies dependently on such an element and most commonly seen as the only design option when compared to other, more costly, construction alternatives. Nevertheless, on large spanning structures which are clear of intermediate supports, the use of either steel structural elements or pre-stressed concrete construction will undoubtedly be the most economical design solution. Below are some of the few design benefits and downfalls which one can expect when choosing to use pre-stressed concrete elements:
BENEFITS
1. Fast and Easy Construction
Pre-cast concrete components lend themselves to fast construction schedules.
Pre-cast manufacturing can proceed while site preparation is underway.
Pre-cast units can be delivered to the job-site and installed the moment they are needed in any weather condition.
Fast construction means earlier completion, eliminating costs of shuttering and resulting in cost savings.
2. Adaptability & Fire resistance
Pre-cast pre-stressed concrete products can be designed and manufactured for any application, ranging in size to accommodate large spanning elements.
Pre-stressed concrete elements gain their fire resistance through increase in concrete cover as per design code requirements. Therefore these are not easily damaged by fire and have low maintenance costs and high corrosion resistance.
3. Durability
Winter construction can proceed with few weather delays as pre-cast components are prefabricated in factory quality conditions.
They provide reliable long-term performance in extremely harsh conditions that could affect other forms of construction (especially when compared to steel structures).
As this technique eliminates weakness of concrete in tension, such members remain free from cracks, hence can resist the effects of impact, shock, and reversal of stresses more efficiently than reinforced concrete structures.
They are resistant to deterioration from weather extremes, chemical attack, fire and accidental damage.
DRAWBACKS
Although pre-stressing has many advantages, there are still some drawbacks in the use of such products:
The unit cost of high strength materials being used is higher as mostly high tensile steel is used.
Extra cost is incurred due to use of pre-stressing elements and their installation.
Pre-stressing is uneconomical for short spans and light loads
Prestressed concrete requires more complex formwork, so it has less design flexibility than other kinds of reinforced concrete, which often makes design more challenging.
The design tools available today give a competitive advantage both in terms of value engineering, design time and presentation. In my opinion, the use of spreadsheets can be less time consuming and more adequate to use in the initial design stages and for estimate purposes. On the other hand, FEA solutions render a more precise output which is more realistic, efficient and economical that is preferable for use in the execution stage of a project.
