Vol.2,No.2,2022-Table of Contents

 

  • Structural analysis of a Guadua bamboo bridge in Colombia
  • Abstract In recent years, scientists have focused their attention in developing sustainable materials that can boost the construction industry without causing damage to the environment. In South and Central American forests grows a tropical species of bamboo known as guadua angustifolia Kunth, which has been widely used for construction purposes since ancient times. Offering advantages such as: environmental friendliness, fast-growing and high strength-to-weight ratio. This paper analyzes the structural behavior of an existing multi-culm guadua bamboo truss type footbridge located in Colombia, according to national regulations NSR-10. A model of the structure is implemented using a commercial finite element software, details for an accurate description of the structure’s behavior through the proposed model are offered. Furthermore, an exhaustive description of the structure’s load transfer and its materials mechanical properties is performed, as well as a review on connections and immunization process. Finally, improvement opportunities for the building codes used for the analysis and investigation opportunities are identified. The purpose of this paper is stepping into the right direction thus, one day guadua angustifolia Kunth and bamboo in general can be fully exploited in the construction industry.… More
  •   Views:576       Downloads:3821        Download
  • Influence of stacking sequence on mechanical properties and moisture absorption of epoxy-based woven flax and basalt fabric hybrid composites
  • Abstract Hybrid composite laminates (HCL) were prepared by lay-up molding using a hot-press bed for reinforcing epoxy-based woven flax and basalt fabric composites. Mechanical properties and moisture absorption of HCL were measured, and the fracture surface was examined by scanning electron microscopy (SEM). The present results indicated that the mechanical properties of HCL are strongly dependent on the sequence of fiber reinforcement. HCL (S2, S3, S4, S5) with symmetric stacking sequences that increase with basalt fibers (wt %) showed a positive hybridization effect on mechanical properties and curve characteristics. However, the mechanical properties of S7 (asymmetric stacking) were lower than S3, S4, S5 (symmetric stacking), which indicated that symmetric stacking sequences of HCL had superior mechanical performance compared with the cross arrangement of HCL. The moisture absorption of HCL samples immersed in water at 26 °C showed the Fickian behaviour up to 42 days and were not affected by altering the stacking sequence on HCL. The SEM of the fracture surface, fiber-matrix bonding, and interfacial bonding of flax-basalt fabric HCL were also presented.… More
  •   Views:809       Downloads:4321        Download
  • Structural response of high strength concrete beams using fiber reinforced polymers under reversed cyclic loading
  • Abstract This paper investigates the response of high strength concrete (HSC) beams subjected to reversed cyclic loading using carbon fiber-reinforced polymer (CFRP), glass fiber-reinforced polymers (GFRP), and hybrid FRP/steel bars as bottom tensile reinforcement. Five HSC beams with a rectangular cross-section were prepared and cast using concrete with a 28-day compressive strength of 60 MPa (8.7 ksi). A displacement-controlled reversed cyclic loading has been applied to all the beams. The test setup has been designed to simulate the forces and boundary conditions that could happen during seismic action. Flexural capacity, concrete and reinforcement steel strains, cracking behavior, and ductility results were obtained. The hybrid steel/FRP has shown an improved performance in terms of flexural capacity, strains, and ductility. While the inclusion of FRP grids reduces the flexural capacity, this can be improved by adding more layers of FRP. The hybrid reinforced sections showed an increase in moment capacity and ductility compared to the FRP only reinforced beams. The mechanistic model predicted values using code ACI 318 and 60% of the given FRP tensile strength were in good agreement with the experimental results. For the hybrid reinforced beams, moment capacities calculated using ACI 440R was shown to be over-estimated. Although ACI 440R designs for externally wrapped FRP, the sectional analysis was performed with the same process as ACI 318.… More
  •   Views:754       Downloads:4463        Download
  • Mechanical properties of timber-concrete connections with steel tube connectors
  • Abstract Composite connections are important components of timber-concrete hybrid systems. This work presents a novel shear connector for timber-concrete composite (TCC) connections. To verify the composite action between the timber and concrete in the proposed connection, ten specimens were subjected to push-out tests to examine the slip at the interlayer. The failure mode and maximum load capacity results are analyzed, indicating that the composite connections have good ductility and high load capacity. Four methods to determine the yield point are compared and discussed in detail. According to the test results, a mathematical model is utilized to predict the nonlinear load-slip curve of the proposed connection. The Bayesian method is introduced to estimate the model parameters and quantify the model uncertainty. The obtained results can be used for further reliability analysis. This work demonstrates that timber-concrete connections with novel connectors perform well and show potential for application in composite structures.… More
  •   Views:854       Downloads:4573        Download
  • Parametric design of developable structure based on Yoshimura origami pattern
  • Abstract Origami is an ancient art form and can be divided into rigid and non-rigid origami. Rigid origami is suitable for the design of building structures because the panels are not twisted and deformed during the folding process. Currently, rigid origami structures are generally built with steel. However, compared with natural, non-polluting wood, steel has a high energy consumption and a high environmental impact. Based on this situation, this paper designs a developable wooden building structure using the Yoshimura origami model. First, the Jacobian matrix method was used to analyze the degree of freedom of the basic unit of the Yoshimura origami pattern, following which the motion trajectory required by the target structure was obtained. Secondly, by analyzing the relationship between the plane angle α and dihedral angle θ, three interaction rules were obtained, and the formula for determining the structure size was established by using the plane angle α, dihedral angle θ, the number of valley folds n and the unit length l. Subsequently, two enhancement schemes, the quadrangle enhancement scheme and the triangle enhancement scheme, were proposed to increase the height of the structure. After comparing the deformation and failure types of origami structures based on Cross-Laminated Timber, a triangular reinforcement scheme was chosen to increase the height of the structure. Finally, a new connection method was developed that allowed the origami structure to be practically applied. This research demonstrates the possibility of developing a timber structure based on Yoshimura origami.… More
  •   Views:1155       Downloads:5572        Download