Optimisation of pre/post-stressed embedment-type timber joint (original) (raw)
Related papers
Frattura ed Integrità Strutturale, 2019
In order to design a seismic timber beam, the effect of near-fault ground motion on timber beam has numerically been investigated, with reference to small displacement theory. The simulated near-fault ground motion is applied on the fixed base of a timber frame model. The beam is placed in single span of a timber frame. The beam has two different length sizes of 1.8 and 3.3 meters. The seismic load-displacement, seismic load-strain and strain-displacement have been calculated for all models and shown in graphs. The beam is designed with nonlinear analysis method and some mechanical properties for all models have been used, in numerical analysis. The numerical analysis results indicate that, the inertial interaction, energy dissipation and nonlinear deformation of beams in timber frames have directly related with frame span. In beams with a smaller length, higher seismic loading caused lower displacement. The displacement is reduced by reducing the length of the beam. The inertial interaction, energy dissipation and nonlinear deformation are changed respect to the length of the beam. The innovation of this paper is to develop cycling graphs by using ABAQUS, to improve design of timber frame and give an adequate explanation of seismic behavior of timber beam.
In most current codes for design of steel structures, specifications for the design of compression members utilize the effective length factor K. This parameter is employed to facilitate the design of frame members by transforming an end-restrained compression member to an equivalent pinned-ended member. The effective length factor is obtained either by solving the exact equations using a numerical iterative solution which may be computationally expensive or by using a pair of alignment charts for the two-cases of braced and sway frames. The accuracy of the solution using the second approach depends on the size of the charts and the reader's sharpness of vision. To eliminate these approximations, simple equations for determining the effective length factor as a function of the rotational resistant at the column ends (GA, GB) are required. Similar equations are available in the French design rules for steel structures since 1966, and are also included in the 1978 European recommendations. In this paper, modifications to the French design rules equations for effective length factors are presented using multiple regressions for a tabulated exact values corresponding to different practical values of the rotational resistance at column ends (GA, GB). The investigated equations are more accurate than the current French rules equations recommended in steel codes of several countries. Comparisons between the numerical results of the equations developed in this study and those obtained by current equations with those obtained by exact solutions are given also in this paper.
Modified traditional Japanese timber joint system with retrofitting abilities
Structural Control and Health Monitoring, 2008
Embedment is a key feature of timber joints envisioned as the ultimate solution in avoiding the devastating full collapse of timber structures in seismic countries. The Japanese traditional timber post-and-beam structural system utilizes moment-resisting joints based on embedment. Despite the joint's advantages having the ductile and energy-absorptive behavior continuously to the post-elastic phases, a primary shortcoming needs to be resolved}specifically of having the low and unreliable initial stiffness due to the gap formation between the contacting members. Further, large-dimensioned timber most suitable for the embedment-type joint is scarce and the lower quality of available timbers is making the modern applications difficult. A new timber joint capable of sustaining future seismic impacts is being pursued using various approaches. As a result of the optimization to satisfy the manifold studies, two traditional elements, namely Kusabi wedge and side-penetrating Nageshi beam, are combined and tightened by the penetrating steel bolt. Its tightening system eliminates the gap formation in the joint, and heightens its performance over the traditional embedment-type joints. Additional features, such as the damage-inducing and fast seismic-retrofitting ability, are also integrated. This new proposal for the 'Kusabi-Nageshi' (K-N) timber joint system aims to provide a new alternative to the joints used in seismic countries.
Hollow Structural Section (HSS) members are known to possess many advantages over equivalent open sections, including better resistance to torsion as well as tension and compression loading, aesthetic appearance and economy in terms of material cost. Connections between HSS members could be made simple by cutting the ends and welding together. However, depending on joint configuration and number of members connected, this may result in complex and expensive connections. This paper presents the results of an analytical investigation done in ANSYS Software. Special attention was paid to T-joints that consist of the chord member of a single square section and brace members of different kinds of cross sections as Square and Circular Hollow sections. A finite element model was developed for 6 specimens to investigate the influence of some variables such as geometry and β-parameter (ranging from β= 0.60 to 1.00) on the joint's response. The brace load (compressional load) was incremented up to joint failure, while the chord was kept unloaded. The Stress-Strain curves were plotted. The force-displacement curves corresponding to the different geometries are analysed and compared, focusing on the failure loads and elastic stiffness. With respect to the geometry, the test results revealed that the use of square hollow section lead to increased joint capacity. With respect to the type of section, it can be concluded that the resistance of a joint with β= 0.75 is greatly influenced by the type of brace member.
The method of displacements calculating in the joints of timber structures
IOP Conference Series: Materials Science and Engineering, 2019
This article is devoted to the peculiarities of calculating compliance modifications of the timber elements on mechanical linkages. Here we analyze in detail the method of C M Kochenov using in the design standards of the Russian Federation. This method allows to determine accurately the number of links that are able to resist the shear force in the linkage, however, this method does not include analyzing of shear deformation in modifications. And it is a disadvantage. In this article the author considers another approach, based on the idea of determining the shear deformation of the mechanical linkage, installed in the connection. To calculate the shear deformations of connections in the linkage it is necessary to conduct a preliminary analysis of the construction, to establish the type of connection and thickness of the connected elements, to determine the number of shear planes, the number of established joints and the level load on the joint. After determining these values, structural analysis design is performed. This article describes in detail the theoretical aspects of this method, used assumptions and limitations. It is considered a test case for validation of the considered methods. The FEM joints model is investigated. The forces and displacements of the bonds obtained by the FEM model are compared with the result of the theoretical calculation.