Competitive Ranges of Timber, Concrete, and Steel Beams Based on Cost Optimization and Sensitivity Analysis, Including CO2 Emission Costs

This paper examines the competitive ranges of timber, steel, and reinforced concrete beams, determined using multi-parameter cost optimization that includes global warming costs (CO2 emissions) associated with beam production. Simply supported beams subjected to self-weight and uniform imposed loads were optimized using discrete mixed-integer non-linear programming (MINLP). The objective functions included material, energy, labor, and CO2 emission costs associated only with manufacturing. Concrete remains the most cost-effective material across nearly all configurations, with glulam and steel being 2.3 and 2.8 times more expensive, respectively. Sawn timber outperforms concrete (by 9.5%) only at short spans (7.5 m) and low loads (10 kN/m1). Environmentally, timber yields the lowest manufacturing footprint, while steel and concrete emit 3.0 and 1.8 times more CO2 than glulam. Currently, CO2 emission costs average just 3.8% of total costs. However, a sensitivity analysis shows that extreme carbon taxes break concrete’s monopoly, increasing its costs by up to 637.4% and making timber the cheapest option for low-to-medium loads. Concrete is resilient to material price shocks at larger scales but highly vulnerable to rising labor rates (up to a 66.3% increase). While current carbon pricing is too low to influence material selection, future substantial tax escalations will shift structural competitiveness toward timber.