Steel Construction Cost Planning is the task to find the sweet spot by optimizing the constraints and requirements of each steel construction trade and deliver the ideal budget.
Steel constructions has various cost drivers. While the weight of a steel structure is a major component of the total cost, the minimization of the cost should be the final objective for optimum use of available resources. The total cost of a steel structure includes the below items.
- The material cost of structural members such as beams, columns, and bracings
- The fabrication cost including the material costs of connection elements, bolts, and consumables and labour cost
- The cost of transporting the fabricated pieces to the construction field,
- The erection cost including the material costs of connection elements, equipment, tools and the labour cost.
2. Weight Optimization
In the steel detailing phase, cost estimates of structural steelwork will break the steel design down into individual components – columns, beams, braces, girts, purlins and so on – and will separately consider connections and fire protection.
When the steel members have been decided, the length and weight of each structural member can be calculated to quantify the total weight. Steel designers tend to minimize the total weight in order to minimize the overall cost however this assumption is mistaken. Past experience shows that raw material cost accounts around 30-40 % of the total cost. Other cost such as fabrication, transportation, erection accounts around 60-70% of the total cost. Therefore trying to minimize the material tonnage will deliver low material cost but it might increase the budget of other operations if the cost drivers of these operations are not taken into account.
3. Availability of the Materials
Due to the steel raw material conditions, it is not possible to find every steel raw material in the market at a given time. The steel designer should be aware of this situation and consider the availability of the steel sections in the market.
Figure 1 : Steel Material Availability
Also, generally, less frequently used steel sections tend to be pricier compared to the frequently used steel sections. Therefore it is recommended to use popular steel sections not only for the availability but also for the unit cost concerns. Close relationships with steel mills and steel fabricators may help to get to learn current and forecasted steel prices.
Also cold formed profile sections such as Z, C profiles are very good substitute for the hot rolled sections in certain applications.
4. Aesthetic Constraints
Figure 2 : Aesthetic Steel Construction
Aesthetic concerns are becoming more dominant in the last decades for the steel constructions. The architects these days are trying more to avoid to conceal the steel frame both interior and exterior. The more they try to expose the steel, the more they have a saying about the type of the steel sections to be used in these areas. Their favourite sections are pipe and hollow section profiles.
Figure 3 :Steel Transportation
The transportation conditions and limitations are a significant determinant of the steel construction design and cost estimation. In general, the more modular a structure, the easier and cheaper will be transportation. But more modular structure means, more parts to be assembled on the jobsite which increases the erection costs. The goal is to find the sweet spot to both minimize the total cost of transportation and erection.
Figure 4 : Steel Erection
Eventually all the steel parts need to be assembled on the jobsite. Due to high labour costs and health and security concerns, the proportion of erection costs in the overall construction budget is on a rise. During the steel construction planning, a smooth and fast erection sequence should be considered to minimize the risks and costs of the erection. The designers should avoid risky or complex joints to simply the erection. The lower the number of parts to erect, the lower the erection costs of the steel building. But the capacity and costs of the lifting equipment should also be taken into consideration in the planning phase.
Steel Construction Cost Planning starts from the early design phases and continues to the end of the project. There are multiple ways how to reduce the cost of steel construction. All parties, architects, steel designer, steel contractor, erection teams and other subcontractors should be involved and should establish an open communication line to deliver a successful outcome. Experiences show that a minor modification in the early stages might lead to significant variations in the overall cost at the end.