Qian Fasheng, Ding Yong, Shi Xinlei, Shu Chengxiao, Zhang Xiaocun
Department of Civil Engineering, Ningbo University, Ningbo, 315211, China.
Ningbo Traffic Planning and Design Institute, Ningbo, 315199, China.
Sci Rep. 2025 Apr 28;15(1):14873. doi: 10.1038/s41598-025-99157-8.
Carbon emissions from bridge engineering are an important component of the carbon emissions in the construction industry. The life cycle carbon emissions (LCCE) of two commonly used simple-supported beam bridges, hollow slab bridge and T-beam bridge, are studied and compared. Firstly, in order to establish the criteria for the comparison of different bridge types, the principle of equal stiffness is proposed for the superstructures, and the principle of matching load effect with bearing capacity is proposed for the substructures. Based on the above two principles, 6 bridges of 2 types and 3 spans are designed for comparative analysis. Then, a calculation model of the LCCE of simple-supported beam bridges is established, in which four stages, production, construction, operation and demolition stages are included, and the carbon emission factors of each stage are established. Finally, the carbon emissions of 6 bridges designed above are calculated, and the main factors affecting the LCCE of simple-supported beam bridges are discussed. The calculation results show that (1) For the same span, the LCCE of T-beam bridges are about 8-10% lower than those of hollow slab bridges. The reasons for this are that T-beam bridges use 22-32% less concrete and 4.5-11.5% less reinforcement than hollow slab bridges, which reduces carbon emissions during the production and demolition stages, and that the durability of the lateral connections of T-beam bridge is better than that of hollow slab bridge, which reduces carbon emissions from the maintenance and repair of T-beam bridge in the operation stage by about 30%. (2) Carbon emissions in the production stage of simple-supported beam bridges account for 83-84% of the LCCE, 11-12.6% of the LCCE in the operation stage, 3.8-4.5% of the LCCE in the construction stage, and 1% of the LCCE in the demolition phase. Therefore, the reduction of carbon emissions is most effective in the production and operation stages of these bridges. (3) Steel and concrete are the two materials that have the greatest impact on carbon emissions of simple-supported beam bridges. 100% recycled steel can reduce the carbon emissions of bridges by 17.7 -19.2% compared with 50% recycled steel. 50% and 100% recycled coarse aggregate concrete can reduce the carbon emissions of bridges by approximately 2.9% and 5.7%, respectively. (4) The carbon emission of the superstructure of the T-beam bridge is 12.5-14.2% less than that of the hollow slab bridge in the same span, and the differences in carbon emissions of the substructures are very small due to the small differences in the loads they are subjected to. With the increase of bridge span, the carbon emission per unit area of the superstructure of simple-supported beam bridge increases, that of the substructure decreases, and that of the whole bridge decreases firstly and then increases, which makes it possible to choose appropriate bridge span to decrease the carbon emission.
桥梁工程碳排放是建筑业碳排放的重要组成部分。对两种常用简支梁桥——空心板桥和T梁桥的生命周期碳排放（LCCE）进行了研究和比较。首先，为建立不同桥型的比较标准，对上结构提出了等刚度原则，对下结构提出了荷载效应与承载力匹配原则。基于上述两个原则，设计了2种类型3种跨度的6座桥梁进行对比分析。然后，建立了简支梁桥LCCE的计算模型，其中包括生产、施工、运营和拆除四个阶段，并确定了各阶段的碳排放因子。最后，计算了上述6座桥梁的碳排放，并讨论了影响简支梁桥LCCE的主要因素。计算结果表明：（1）对于相同跨度，T梁桥的LCCE比空心板桥低约8-10%。原因是T梁桥比空心板桥少用22-32%的混凝土和4.5-11.5%的钢筋，这减少了生产和拆除阶段的碳排放，并且T梁桥横向连接的耐久性优于空心板桥，这使得T梁桥在运营阶段的维护和修复碳排放减少了约30%。（2）简支梁桥生产阶段的碳排放占LCCE的83-84%，运营阶段占LCCE的11-12.6%，施工阶段占LCCE的3.8-4.5%，拆除阶段占LCCE的1%。因此，在这些桥梁的生产和运营阶段减少碳排放最为有效。（3）钢材和混凝土是对简支梁桥碳排放影响最大的两种材料。与50%再生钢相比，100%再生钢可使桥梁碳排放减少17.7-19.2%。50%和100%再生粗骨料混凝土可分别使桥梁碳排放减少约2.9%和5.7%。（4）在相同跨度下，T梁桥上结构的碳排放比空心板桥少12.5-14.2%，下结构的碳排放差异很小，因为它们承受的荷载差异很小。随着桥梁跨度的增加，简支梁桥上结构的单位面积碳排放增加，下结构的单位面积碳排放减少，全桥的单位面积碳排放先减少后增加，这使得选择合适的桥梁跨度以减少碳排放成为可能。
