International Journal of Advanced Structural Engineering
This paper investigates the mechanical performance of longitudinally cracked glulam columns under eccentric compression loads. Experimental investigation was conducted to explore the influence of initial cracks on the failure modes and load bearing capacity of glulam columns. Two different crack patterns named DC and IC, and two column lengths (i.e. 600 and 1100 mm) were considered in the experiments. It was indicated that these two crack patterns reduced the capacity of slender glulam columns and the difference of failure modes was observed between glulam columns with and without initial cracks. Further, a numerical model was developed and validated by the test results. With the application of cohesive zone material model, the propagation of initial cracks could be considered in the numerical modeling. A parametric study was carried out by the verified model and the influence of crack lengths and crack locations was further investigated. From the numerical analysis, it was found that through cracks reduced the capacity of glulam columns significantly. Also, crack location impacts the capacity of glulam columns and the extent of impact relates to the slenderness ratio of the columns, while cracks with different lengths have similar influence on the capacity of columns.
In this study, five full-scale bolted glulam beam-to-beam connections with slotted-in steel plates were conducted under a third-point loading, and a three-dimensional finite element method based model was also established to investigate the failure modes and moment resistance of such connections. A material model based on the Continuum Damage Mechanics (CDM) theory was developed to predict damage evolution of wood. Different damage variables were used to consider the ductile and brittle failure modes of wood, respectively. The test results indicated that splitting and shear plug failures were the main failure modes. The numerical analysis model prediction achieved fair agreements with the test results. The research could provide the guide for the design of bolted beam-to-column connections in heavy timber structures.
Moment resisting joint with lagscrewbolts shows good mechanical performance and aesthetic. However, beam and column joints rarely showed a brittle shear failure in a panel zone of a column in previous studies. Therefore, a joint system reinforced by long screws was developed to prevent from the failure in this research. The maximum shear strength of the joint increased with increasing the number of long screws. However, the average of six screws specimens was lower than that of four screws, because the glulam and some of the screws were damaged due to the narrow space between the screws during an inserting process of the screws.
Although it was found that most of the research foci were on reinforcement of timber connections and flexural members, columns and shear walls play a crucial role in the prevention of structural collapse. Recent trends to build taller timber structures, a demand for structures with larger span, and re-use of existing structures for different purposes have made reinforcement of timber columns and shear walls increasingly important. In addition, repair of damaged timber columns and shear walls so as to prevent further damage to the structures and elongate the life span of existing structures is also important. This paper provides an overview of techniques available to repair and strengthen timber columns and shear walls in both research and practice.
This study presents the experimental evaluation of the behaviour of beams and columns made of Glued Laminated Guadua (GLG) bamboo. Flexural tests were conducted on structural size beams of various span lengths and two lamination orientations (horizontal and vertical) in order to evaluate the different capacities achieved according to the predominant induced stresses, bending or shear. Experimental results indicated a reduction of bending strength as the member’s size increased whereas lamination in the vertical direction presented 12% higher values of modulus of rupture (MOR), and 9% higher values of modulus of elasticity (MOE) compared to equivalent results for lamination in the horizontal direction. Additionally, compression tests were performed on structural size columns with various slenderness ratios and two lamination orientations. Although minor differences were found for lamination orientation, lower capacities were observed as the slenderness ratio increased. This experimental data is expected to be used in order to propose adjustment factors for structural size beams as well as the determination of the column stability factor.
This paper presents preliminary results from an experimental program investigating the dynamic behaviour of glulam beams and columns subjected to simulated blast loads. A total of eight glulam beams and columns were tested destructively under static and dynamic loads. Based on the dynamic tests conducted on the beams, an increase in strength under dynamic loading, relative to that measured under the static loading, was observed. A material predictive model that accounts for high strain-rate effects is developed. The experimental displacement-time histories were reasonably well predicted through a single-degree-of-freedom approach which used the proposed resistance model as input.
In this paper, bending behaviours in hybrid composite glulam timbers reinforced using deformed steel bars and epoxy resin adhesives (RGTSB) are presented. The technique RGTSB was developed in order to improve flexural stiffness and strength in glulam timbers...
Dovetail connections were applied for connecting column to column, and beam to beam in traditional timber framed buildings. Previous studies were mainly focused on mechanical behaviour of the connection. However, there was a lack of study on the structural behaviour of the connection under different moisture contents. The goal of this study was to analyse the effects of moisture content on swelling behaviour and structural performance of dovetail connection. Different sizes of 120×120, 180×180, 180×240 mm from larix kaempferi and pinus koraiensis were used. Dimensional changes of dovetail connection made from different species showed different trends with an increment of size. The dimensional changes of member of dovetail connection from larix kaempferi were higher than those of dovetail connection made from pinus koraiensis, whereas the dimensional changes of geometric variables of dovetail connection from pinus koraiensis were higher than those of dovetail connection made from larix kaempferi.
The Tallwood House project was intended to advance the design and
manufacture of mass timber products in Canada and demonstrate
that mass timber is a viable structural option for mid-rise and
high-rise buildings. The use of mass timber and engineered wood
products in high-rise construction is becoming more common
around the world leading to a growing interest in the performance of
mass timber over time.
This report describes the performance of the mass timber structure
in Tallwood House, between September 2017 and August 2019,
based on measurements of the moisture content in the prefabricated
CLT floor panels and the displacement of the vertical structural
system. It is intended to initiate discussions on the performance of
mass timber structure elements during building occupancy and lead
to further research that can explore the influential factors.
The joints are very important structural element in timber framed structures. The purpose of this study is to develop the high-strength and high-ductility beam-column joint for timber structure. In this study, steel plate fastened with drift pins and paste the ultraviolet-ray hardening Fiber Reinforced Plastics (FRP) on the surface of the member section. The wood is the anisotropic material of which the strength characteristic greatly differs according to the direction of the fiber. The strength of the fiber direction is high, but the strength of the fiber orthogonal direction is low. Also, the splitting failure is caused in the fiber orthogonal direction, and there is a case in which strength and toughness extremely lower. It is necessary to consider the weak point of such woody material for the case in which the wood is used as a structural element for timber framed structure. It is very important to be ensured the earthquake-proof safety of the building, and prevent a building collapse for the great earthquake. This study reinforces weak point on the strength of woody material by using the ultraviolet-ray hardening FRP. Then, timber framed joint of the high-strength and high ductility is developed as a structural element. In this study, the verification experiment is carried out for the joint element specimens of the large section wood.