The Corrosion Characteristics and Tensile Behavior of Reinforcement under Coupled Carbonation and Static Loading
This paper describes the non-uniform corrosion characteristics and mechanical properties of reinforcement under coupled action of carbonation and static loading. The two parameters, namely area-box (AB) value and arithmetical mean deviation (Ra), are adopted to characterize the corrosion morphology and pitting distribution from experimental observations. The results show that the static loading affects the corrosion characteristics of reinforcement. Local stress concentration in corroded reinforcement caused by tensile stress drives the corrosion pit pattern to be more irregular. The orthogonal test results from finite element simulations show that pit shape and pit depth are the two significant factors affecting the tensile behavior of reinforcement. Under the condition of similar corrosion mass loss ratio, the maximum plastic strain of corroded reinforcement increases with the increase of Ra and load time-history significantly.
Strength and ductility of corner materials in cold-formed stainless steel sections
Abstract The cold work from the manufacturing process of cold-formed steel members can enhance the strength but reduce the ductility of materials. Due to a high cost of stainless steels, it is desirable to utilize this enhanced strength and avoid the early fracture in cold-formed stainless steel members. The paper is concerned with the prediction of the enhanced stress–strain behaviour and reduced ductility of corner materials in cold-formed stainless steel sections. The enhanced strength of corner materials has been traditionally determined using empirical models. However, most of these empirical models are only able to predict the enhanced 0.2% proof strength, but are neither capable of predicting the enhanced ultimate strength nor able to determine the reduced ductility. This paper first presents a modified weighted-average method for predicting the post-ultimate stress–strain behaviour and the fracture strain for stainless steels. An advanced numerical approach is next presented for predicting the full-range stress–strain behaviour of corner materials in cold-formed stainless steel sections, in which the modified weighted-average method is incorporated. The accuracy of this approach is demonstrated by comparing its predictions with test results. The proposed approach is generally applicable to cold-worked materials for predicting their enhanced strength, reduced ductility and full-range stress–strain behaviour. The proposed method and numerical results can explain why and how the ultimate strength of cold-formed steels can be increased and how the post-ultimate stress–strain behaviour can be utilized through cold working.
Catalytic Vapor Cracking for Improvement of Bio-Oil Quality
Bio-oil has attracted considerable interest as a promising renewable energy resource because it can be utilized as a feedstock in integrated bio-refineries for the production of highly valuable chemicals and next-generation hydrocarbon fuels. However, it is necessary to improve the bio-oil quality before it can be fed to bio-refineries. Currently, catalytic vapor cracking seems a more attractive process than catalytic upgrading technologies, such as hydrotreating and esterification, in order to improve the bio-oil quality. This review presents a summary of recent research and the state of art technology for the catalytic vapor cracking of bio-oil, focusing on the catalysts applied, upgrading methods and reaction mechanisms.