317 publications from this institution
In order to improve the durability of reinforced concrete member, fiber reinforced polymer (FRP)-reinforced concrete member is introduces. Monotonic loading was applied to a reinforced concrete beam and FRP-reinforced concrete beam, in order to investigate the failure progress and characteristics of FRP-reinforced concrete beam.. The presenting study provide a basis for improving the design method for FRP-reinforced concrete member.
To improve the negative influence on the structural members from the failure brittleness of the ultra-high performance concrete (UHPC) and enhance the load-bearing capacity and deformability of the structural members, the fiber-reinforced polymer (FRP) confined UHPC columns have been proposed and are attractive in practical engineering. The performance of the unconfined and FRP-confined UHPC cylinders under axial compressive load was investigated experimentally. The following conclusions can be drawn from this study. For the FRP-confined UHPC cylinders with low, medium or high confinement levels, the stress-strain relations showed three kinds of behavior. Based on the analysis of the lateral strains of FRP and the shear-slip deformation patterns of UHPC cylinder, a three-stage failure mechanism for the FRP-confined UHPC cylinders under compression was proposed in this paper, including: (I) the formation of microcracks, (II) the formation of shear cracks, and (III) the formation and propagation of major shear cracks. Besides, design-oriented equations for predicting the ultimate compressive strength and ultimate axial strain were proposed, in which the confinement stiffness ratio and the strain ratio were considered as essential parameters.
No abstract is provided for this article.
The utilization of coral aggregate concrete (CAC) in marine construction has drawn the attention of engineers and researchers in recent years. Due to the high content of chloride in CAC induced by coral aggregates and sea water, reinforcing CAC with traditional material, i.e., steel, can cause serious corrosion-related durability problems. Replacing steel with corrosion-resistant fiber-reinforced polymer (FRP) has been considered a promising solution. This paper provides insight into the bond behavior between CAC and FRP bars. In total 30 pull-out tests were conducted. The investigated variables included the concrete matrix, FRP bar type, bar diameter, and thickness of concrete cover. Based on the test results, discussions on the bond failure modes, influencing factors of bond strength and bond stress-slip relationship were presented. For splitting failure mode and pullout failure mode, empirical bond stress-slip models were proposed respectively. Adopting the failure criterion of CAC proposed in a previous study, a mechanical model for bond strength under pullout failure mode was developed. Comparisons with test results validated that the proposed models provide reasonable predictions for the bond properties between GFRP bars and CAC.
The writers would like to express their gratitude to Dr. Yang Zhan and Dr. Ben-ben Li for their thoughtful and valuable comments as well as acknowledging the contribution of the original paper. The writers provide the following response and clarifications to the points raised by the discussers:
The idea of structural art has gained an increase in interest due to the pioneering book by David Billington in 1983. With this, a paradigm shift is emerging with the belief that structural engineers can become artists in the design process by cooperatively integrating three tenets: economy, efficiency, and elegance. The objective of this up-to-date review is to present a broad perspective of structural art during the past three decades (1983–2013). Historical engineering projects and the stories of their structural engineers are discussed to identify the key conditions that have contributed to various works of structural art. Further, this review promotes the importance of the structural art concept and equips future engineers by discussing the potential resources and tools that can be utilized to learn more about structural art.
Gypsum-based composites (GCs) have been widely used in interior linings such as walls and ceilings due to their unique advantages including low cost, good habitability, and good fire resistance. The existence of many gypsum resources such as natural gypsum (NG) and industrial gypsum by-products ensure that GCs are very popular. The main weaknesses of GCs, especially those originating from industrial gypsum by-products, are brittleness, inferior mechanical properties, and low water resistance, which limit their further applications. Extensive studies have used fibres to enhance the performance of GCs. Fibre-reinforced gypsum-based composites (FRGCs) show excellent comprehensive performance and have wider marketability as building materials, which is beneficial for accelerating the utilization of gypsum by-products and creates many economic and environmental benefits. This paper reviews previous studies of GCs reinforced with fibres and summarizes, reviews, and discusses the sources and properties of gypsum and fibres, the pretreatments of fibres to improve their adhesion with the matrix, the effect of fibres on some properties of FRGCs, the application of FRGCs in three-dimensional (3D) printing and the challenges for further research. This review provides a foundation and guide for future studies and uses of FRGCs.
Fiber reinforced polymer (FRP) textile, as the continuous reinforcement of multi-scale fiber reinforced cementitious composite (MSFRC), is expected to be widely applied due to the high strength, lightness, anti-corrosion and ease of installation. In this work, the unique features of FRP textile, characterized by initial delayed stiffness and strength efficiency, are investigated thoroughly. First, the direct tensile tests, comprising FRP textile and MSFRC plate specimens, are performed by varying the number of the textile ribs and layers. On this basis, an analytical approach for FRP textile is proposed based on the digital geometric model and Monte Carlo simulation. The considered distributions of textile properties include the stochastic slacks and strengths of different ribs. Then, a good agreement can be found between the experiments and the simulations. Finally, the bilinear model of FRP textile is further developed using the proposed model to serve as a basis for the reliable structural design.
The object of this study was to evaluate the effect of lead and cadmium stresses on growth and development of perennial ryegrass and to better understand the potential of perennial ryegrass for phytore mediation of Pb and Cd contaminated soils,and provide technical information for soil remediation planning.In a pot experiment,Pb was spiked at 0,300,500,1000,1500 mg/kg,and Cd was spiked at,0,0.3,3,10,50,100mg/kg.Further,Pb and Cd treatments were combined as follows:Pb_0Cd_0(CK),Pb_(300)Cd0.3,Pb_(500)Cd_(0.3),Pb_(1000)Cd_(0.3),Pb_(1500)Cd_(0.3),Pb_(300)Cd_(10),Pb_(500)Cd_(10),Pb_(1000)Cd_(10),Pb_(1500)Cd_(10).Measurements made included germination vigor,an establishment rate index,chlorophyll content,photosynthetic rate,transpiration,water use efficiencies of seedlings,as well as photosynthetically active radiation,and light use efficiency.The Pb and Cd contents of root,stem and leaf were determined in the seedlings.Compared to CK,there was no significant difference in germination at lower concentrations(300,500mg/kg)of Pb stress,but there was an adverse effect at higher concentrations(1000,and 1500 mg/kg).Lower concentrations of Cd stress promoted seed germination,but where Cd concentration was more than 10mg/kg,there was inhibition of seed germination.With increase in Pb concentration,chlorophyll content also increased,but Cd stress the opposite tendency was noted.Photosynthetic rate decreased at lower concentrations and then increased at higher concentration under Pb or Cd single stress.Photosynthetic rate peaked when Pb concentration was 1000mg/kg or Cd concentration was 10mg/kg.The enrichment coefficient decreased with increase in concentration of the metals Pb or Cd.The Pb and Cd combinations showed stronger inhibitory effects on seed germination than single metal exposure stress.The enrichment ability of perennial ryegrass to Pb and/or Cd was rootstemleaf.The enrichment coefficient of Cd was greater than that of Pb.Perennial ryegrass showed a better remediative effect on lightly polluted soils.
合理的种植密度有利于提高高粱的生产潜力。本试验为了阐明矮秆早熟高粱品种‘吉杂141’在佳木斯地区的合理播种密度,在大田试验条件下,设置了15万、20万、25万、30万、35万株/hm~24种播种密度,研究不同密度对产量及产量性状的影响。结果表明：随着种植密度的增大,叶面积指数增加,叶绿素含量下降,株高差异不显著,穗长、穗粗逐渐下降,生物产量随着密度的增加而增加,千粒重和单穗重对产量影响最大,二者与产量均呈正相关关系。在佳木斯地区,‘吉杂141’最适播种密度为20万株/hm~2,产量可达到9183.00 kg/hm~2。为该品种在本地的推广和应用提供了理论依据和技术支撑。
The steel bar connection is an important and inevitable work in civil engineering. The traditional overlapped connection method usually needs to place the transversal rebars in the overlapped splicing area to restrict the splitting cracks in concrete. The steel usage and labor cost are increased. An improved splice, which is the hybrid connection of welding and overlapping, was developed for mid-diameter bars, which is easy to install and has commendable mechanical behavior. A series of reinforcing rebar splice tests with steel-concrete interaction were conducted. The failure model of hybrid connection and the ultimate strength were acquired. Based on the tests, the failure mechanism of hybrid connections was analyzed. The results show that the ultimate load of the new splice is sufficient for the engineering application and the failure model is reasonable. The hybrid connection could be used in the engineering practice.
The shear stiffness of novel blind bolts was experimentally investigated for shear connections within steel-FRP composite beam systems using steel-FRP joints loaded in tension. The number of bolt rows (either one or two bolt rows) and the effect of the pultrusion orientation of the FRP web-flange sandwich slab on joint stiffness and joint capacity were examined. It was found that joint capacity and failure modes were dependent on the pultrusion configuration of the FRP slab and the number of bolt rows. A unidirectional configuration consisting of an FRP slab with box-profiles parallel to flat panels exhibited shear-out failure, whereas a bidirectional orientation consisting of an FRP slab with box-profiles perpendicular to flat panels exhibited both shear-out and net-tension failure in the FRP component. The experimentally derived shear connector stiffness was then used in a proposed design formulation to predict the bending stiffness of modular steel-FRP composite beam systems, considering two kinds of partial composite actions. These were the composite action provided by the blind bolt shear connector and the composite action provided by transversely-oriented webs within the slab. Good agreement was observed between the experimental results and the proposed design formulation.
An all-GFRP bay window for residential buildings is developed for energy conservation, low carbon, and comfortable life. The durability performance and design of GFRP bay window in an outdoor environment are investigated experimentally. Relevant studies were first reviewed, and the reported findings were found to significantly vary and could not be directly adopted. To investigate the durability of a GFRP material used in an outdoor environment, four aging tests were conducted, namely, water immersion, wet-dry cycle, freeze-thaw cycle and ultraviolet radiation tests. Visual inspection and scanning electron microscopy were used to evaluate the aging effects on the material. In addition, the weight, Barcol hardness, and tensile and flexural properties of the aged GFRP material were measured after the aging tests. Water immersion had the greatest effect on the mechanical properties of the GFRP material, while the freeze–thaw cycle had a negligible influence. Furthermore, to assist in the design of an all-GFRP bay window with a service life of 50 years, a design method was proposed based on the experimental results obtained in this work. This method is the first to directly support the practical design of the long-term behavior of GFRP structures in China and has great potential to be widely adopted in the future.
In this short communication, a series of novel forms of tubular members made of fiber-reinforced polymer (FRP) grid reinforced ultra-high-performance concrete (UHPC) (referred to as “FRP-UHPC tubular members”) are developed. FRP-UHPC tubular members have excellent mechanical properties, and their excellent performances are demonstrated through three preliminary studies: i) behavior of FRP-UHPC tubular beams under bending; ii) behavior of FRP-UHPC tubular columns under axial compression; and iii) behavior of FRP-UHPC plates with a novel grouting sleeve connection system under bending. The experimental programs and results are briefed in the paper. The proposed FRP-UHPC tubular members are attractive in various structural applications such as pipelines, bridge box girders, permanent formwork of beams/columns, especially in marine environments (e.g., floating structures).
