Papers by Author: Yan Xiao

Abstract: Glubam is a kind of environmentally friendly and energy efficient composite material in civil engineering developed in recent years. But the mechanical performance after subjected aging under the outdoor conditions is a blank of research field. In this paper, a new artificial accelerated aging test method and equipment for glubam have been presented by authors. The basic material performance, including deformation changing, tensile properties, compressive properties, bending properties and internal bonding strength, are tested according to the equivalent aging duration of 120 days, 240 days, 480 days and 960 days. The failure mode of specimens shows that delamination of glubam caused by dry wet circulation is the main reason for mechanical properties degradation. All test results present monotone decreasing trend and the internal bonding strength is the most sensitive to aging duration. Aging influence factor β, internal bonding correlation coefficient η and internal correlation coefficient θ can be used to evaluate aging performance of glubam, but the accuracy of evaluation results need further research.

Abstract: Glubam is a new construction material and glubam bolted joints have been developed in modern bamboo structures. To observe the performance of bolted joint, two major groups of glubam-single-bolted-joint specimens with double steel side plates are tested. Bearing strength and failure mode are analyzed and discussed. It is shown that specimens with tension parallel to bamboo fiber always yield by shearing out and showed higher bearing strength as well as better ductility, while specimens with tension perpendicular to bamboo fiber will fail by net tension. Results of bearing strength are evaluated by the 5% off-set method. At the end, equations obtained from test data and analysis about yielding strength of glubam bolted joint was obtained for following study and project design.

Abstract: Based on the practice of the landscape sketch bamboo buildings of Meixi Lake in Changsha, this thesis, from the perspective of material construction, aims to perceive the region and bamboo structure, to concern the bamboo frame form and space construction, to try to integrate bamboo structure with other materials and to explore the formation of bamboo-framed building and the related regional expression. Excavating bamboo value, improving bamboo performance and developing bamboo structural building can satisfy requirements as the main part of construction and expression in architecture and promote the using level of GluBam. Technological innovation such as suitable construction skills and reasonable structural system can promote the effective utilizing bamboo and development of modern bamboo structure. It is a alternative green building system for sustainable development.

Abstract: A full-scale testing model of laminated bamboo truck load bridge was made based on the original structure. The mid-span deflection of CFRP-reinforced bamboo girders, temperature and relative air humidity were obtained through over three years creep test under self-weight, and the analysis based on experimental results was finished. The results indicate that the average creep deflection of the girders after three years is approximately 8-mm. In addition, the increase in temperature and humidity may contribute to creep. On the basis of creep test, a short-term loading test was carried out applied with dead load, and the bridge collapsed under the load of 18.5-t. By the analysis of the experimental results, it is realized that long span CFRP-reinforced bamboo girders have sufficient capacity to meet the strength and durability needs of practical use. Although CFRP layers could improve the performance of bamboo girders effectively, there is a decrease in strength and stiffness when considering the long-term performance. All these studies may contribute to improving the design of bamboo bridge structures, and some construction measures are suggested for the bamboo bridge according to the results of the experimental and analysis results.

Abstract: This paper reports the first step of a study to evaluate the lateral resistance capacity of Round bamboo shear walls and its mechanical properties under Monotonic and cyclic loading conditions. The bamboo shear walls are built with round bamboo as its stub and with ply-bamboo sheet as its sheathing. Load-displacement curves of six round bamboo shear walls, with three different connection types, were obtained in this experiment, and the test results showed that the lateral resistance capacity of round bamboo shear walls can exceed 4.0kN/m, satisfying the projects requirement. A combination of nail and panel failures were observed in the test.

Abstract: During earthquake, the inelastic action in the plastic hinge regions of structures and bridges results in significant reversed deformation and failure of the critical components because of cumulative damage. To simulate seismic behavior of structure members and develop a simplicity damage criterion for circular concrete filled steel tubular (CFT) columns subjected to a series of earthquake excitations, an experimental study was undertaken to investigate the cumulative damage and relationship between low cycle fatigue life and displacement amplitude. Two types of large scale circular CFT columns with different kinds of seam weld and inner concrete compressive strength including nine specimens were tested under quasi static loading with constant and variable cyclic amplitudes. The test data were evaluated with the fatigue model relating deformation and fatigue life. Fatigue life expressions for application in damage-based seismic design are developed.

Abstract: This paper experimentally investigated the effects of axial load level on the residual strength and stiffness of concrete-filled steel tubular (CFT) stub columns which were heated and cooled down to room temperature under sustained axial load. Eight stub columns were axially loaded and heated to specified high temperatures in a purpose-built electric furnace. After the specimens cooled down to room temperature while the axial load was kept constant, the stub columns were loaded to failure. The test results show that not only the axial load level and the high temperature exposure have significant effects on the residual strength and stiffness of stub column, but the residual strength index and stiffness index of the fire-damaged CFT stub columns with pre-load are remarkably different from those without pre-load. From the test results, it is recommended that the sustained axial load effects and the fire cooling phase should be taken into consideration in assessing the fire-damaged CFT columns.

Abstract: Seismic response of a multi-span bridge is investigated in this study using an Internet based testing platform. The platform, NetSLab, was developed based on client/server concept along with a proposed data model and communication protocols. The platform is capable of transferring control and feedback data and signals among remotely located structural testing laboratories or computers connected by Internet. In these tests, a three-pier bridge system was simulated in which a Glass Fiber Reinforced Plastic (GFRP) retrofitted reinforced concrete pier was tested physically in Hunan University and a Carbon Fiber Reinforced Plastic (CFRP) reinforced concrete retrofitted pier was tested physically in Harbin Institute of Technology and the third one was simulated numerically in Tsinghua University. The bridge was loaded to simulate the responses under ground motions corresponding to earthquake hazards for a highly seismic location with 63%, 10%, 2% chance of exceedance in 50 years. The experiments demonstrate that the bridge structure with retrofitted piers has adequate behavior under earthquake loading even in areas of high earthquake intensity.

Abstract: A networked structural laboratories system for seismic simulation of structures is presented. It consists of an independent network based communication platform (NCP) and various applications based on NCP. The NCP was developed based on client/server concept along with a proposed data model and communication protocols. It is capable of transferring control and feedback data among computers connected by Internet that is a hierarchical network with ubiquitous deployment of middleboxes, such as firewalls and network address translators. Communication speed tests were conducted in various network environments. Applications for hybrid dynamic test of bridge and building structures have been developed and remote hybrid tests of structures were carried out among the Hunan University, the Harbin Institute of Technology, and the Tsinghua University.

Abstract: In order to improve the constructability and meanwhile ensure excellent seismic behavior, an innovative bolted endplate connection to steel beam and reinforced concrete column (RCS) was developed, and three full scale model joints with or without floor slab were tested under simulated seismic loading. The proposed composite joint is characterized by an extended endplate which is welded to steel beam with reduced sections in factory and then bolted to reinforced concrete column using high-strength steel rods in field. The effect of material strength and concrete floor slab on the seismic behavior of joints was studied. Experimental results indicated that both specimens without floor slab exhibited good ductility and energy-dissipating ability with full plastic hinging formed at the reduced sections of steel beam. However, owing to the effect of floor slab, the beam sections became unsymmetrical and positive moment strength of the joint was increased significantly. The specimen with floor slab fractured at the weld between the bottom flange of the beam and the endplate, and the failure mode resembled what occurred during the Northridge earthquake.