Comparison of environmental performance of steel and reinforced concrete buildings by linear and nonlinear analysis

Abstract

There has never been a better time to save energy, but every start would be smart. Buildings play a remarkable role in human civilization, however, at the same time, are responsible for the largest energy consumption and Green House Gas emissions around the globe. Due to the alarmingly increased concern raised towards the environmental sustainability, engineering design trends change mildly during the past few decades and efforts have never been enough towards the realization of real energy-efficiency improvement. The energy efficiency of municipal landmarks, residential buildings and commercial high-rises has increasingly been improved in different ways and fields to combat the battle towards energy sustainability, supply security and economic competitiveness. Many countries and cities, including Hong Kong, have launched policies or actions to control and reduce the embodied energy and emissions of buildings by the application of low-carbon construction materials. In view of this, the Construction Industry Council has launched a Carbon Labelling Scheme for Construction Products for industry players to select 'low carbon'materials'. On top of that, alternative structural design might further reduce the embodied carbon at a building system level. In addition to the essential requirements on quality and safety of a building, embodied carbon can be integrated in the structural optimisation process to generate low carbon construction design. Nonlinear analysis method has showed its advantages in many areas along its developing history. As its application has been more and more popularly recognized and suggested by officially published design codes, the advantage of nonlinear analysis in terms of environmental performance enhancement would be worth of further exploration. This thesis serves as a fulfilment of the final assessment of the PhD research study, aiming at addressing this environmental advantage that nonlinear analysis would be able to bring to the field of structural design, due to its capability to optimise the use of building materials in construction without over-designing redundant members and under-designing critical members. Based on this technique, the environmental impact of using steel, composite and reinforced concrete structures will be evaluated in a scientific manner. The importance of environmental performance would be addressed firstly followed by an overview of the background and literature preparation for the basis formation for the comparison study to be carried out. Structural models in both steel and reinforced concrete would be established tobe analysed and designed through both conventional linear method and nonlinear method. Typical building design cases fulfilling Hong Kong design background and requirements have been analysed and demonstrated. Results have been collated through the quantification and mitigation of total embodied carbon (EC) in a system level for all steel, reinforced concrete (RC) design buildings and even with composite floor system at different heights, with or without underground consideration, through the scientific integration of low carbon materials and Nonlinear Structural optimisation. An environmental advantage target is to be achieved through the comparison in terms of material consumption, embodied energy and embodied carbon, followed by a potential economic aspect, nonlinear analysis would be able to bring to the field of structural design. Low carbon building design options interms of different design purpose or materials will be provided for the future reference of developers and engineers.