Strength and stiffness of glulam trusses with punched metal plated joints

1993 ◽  
Vol 20 (4) ◽  
pp. 622-630
Author(s):  
Erol Karacabeyli ◽  
Conroy Lum ◽  
Link Olson
Keyword(s):  
Key Words ◽  
Failure Modes ◽  
Technical Information ◽  
Manufacturing Plant ◽  
Design Load ◽  
Metal Plates ◽  
Glued Laminated Timber ◽  
Parallel Chord ◽  
Strength And Stiffness ◽  
Plate Failure

Several Canadian wood truss manufacturers expressed a need to develop technical information to initiate the fabrication and acceptance of wood trusses made with glued-laminated timber (glulam) members and connected by punched metal plates. In collaboration with industrial participants, Forintek Canada Corp. developed a program for testing and analysis of metal plated glulam trusses. Twelve 3/12 pitched chord trusses and three parallel chord trusses, all 13.7 m long, were designed by three different plate manufacturers. All truss fabrication took place at a single truss manufacturing plant. Trusses composed of 79 mm wide and 152-229 mm deep glulam members connected by 16-gauge punched metal plates were tested to failure. The ratio of ultimate to design load averaged 3.5, and varied between 2.7 and 4.4. Both wood and plate failure modes were observed. The results suggest that the sizes of glulam members used in this study are structurally suitable for use with 16-gauge metal connector plates. Key words: wood, trusses, glued-laminated timber, truss plates, strength, stiffness.

Agroforestry practices in leasehold forests in Tanahun, a Mid-hill district of Western Nepal

1970 ◽  
Vol 16 (2) ◽  
pp. 45-49
Author(s):  
R Shakya ◽  
SK Baral ◽  
R Basukala ◽  
S Khanal
Keyword(s):  
Key Words ◽  
Traditional Knowledge ◽  
Poverty Alleviation ◽  
Technical Information ◽  
Environmental Conservation ◽  
Forest Product ◽  
Degraded Lands ◽  
Hill District ◽  
Dual Objectives ◽  
Agroforestry Practices

(Author of this paper, S Khanal was omitted in error - added on 29-3-2010)Leasehold forestry in Nepal has sought to address both poverty alleviation and environmental conservation. The major agroforestry practices observed in the leasehold forests were silvopasture, hortisilviculture and Non Timber Forest Product (NTFP) cultivation. The most prominent problem to the users in adopting agroforestry practices was the lack of technical information. Some successful insights observed suggest that agroforestry has a notable potential to address dual objectives of poverty alleviation and conservation. The need to evolve sustainable mechanism for promoting agrofrorestry in degraded lands through the dissemination of useful traditional knowledge, innovative practices and improved technologies was identified. Key words: Leasehold forest; agroforestry; silvopasture; hortisilviculture; NTFP Banko Janakari Vol.16(2) 2006 pp.45-49

Analysis on Metal Plate Connection Property of Larch Dimension Lumber

2012 ◽  
Vol 174-177 ◽  
pp. 2170-2175
Author(s):  
Rong Jun Zhao ◽  
Jun Zhen Zhang ◽  
Hai Bin Zhou ◽  
Ben Hua Fei
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Metal Plate ◽  
Seismic Structure ◽  
Performance Parameters ◽  
Metal Plates ◽  
Dimension Lumber ◽  
Design Value ◽  
Plate Connection ◽  
Ductility Ratio

In this study, Larix gemilinii and metal plate were selected as the main materials. According to GB5005-2003, the connection properties of tension-splice joint and larch wood were investigated. The results showed that the elastic modulus of Larix gemilinii was not affected by the performance parameters of tension-splice joint greatly and three kinds of failure modes were introduced. Besides the design value for the ultimate bearing capacity of Larix gemilinii and the design value for the ultimate tensile bearing capacity of the metal plates were determined. A conservative calculation method for ductility ratio of metal plates was proposed. The ductility ratio of the metal plate connected joint changed with the construction modes, and the ductility ratio for metal plate parallel to the grain (more than 2.4) was obviously bigger than that of perpendicular to the grain, which complies with the requirements for ductility ratio in anti-seismic structure.

Effects of infill patterns on the strength and stiffness of 3D printed topologically optimized geometries

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nadim S. Hmeidat ◽  
Bailey Brown ◽  
Xiu Jia ◽  
Natasha Vermaak ◽  
Brett Compton
Keyword(s):  
Material Properties ◽  
Failure Modes ◽  
Mechanical Anisotropy ◽  
Failure Behavior ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Orthotropic Composite ◽  
Material Extrusion ◽  
Specific Material ◽  
Strength And Stiffness

Purpose Mechanical anisotropy associated with material extrusion additive manufacturing (AM) complicates the design of complex structures. This study aims to focus on investigating the effects of design choices offered by material extrusion AM – namely, the choice of infill pattern – on the structural performance and optimality of a given optimized topology. Elucidation of these effects provides evidence that using design tools that incorporate anisotropic behavior is necessary for designing truly optimal structures for manufacturing via AM. Design/methodology/approach A benchmark topology optimization (TO) problem was solved for compliance minimization of a thick beam in three-point bending and the resulting geometry was printed using fused filament fabrication. The optimized geometry was printed using a variety of infill patterns and the strength, stiffness and failure behavior were analyzed and compared. The bending tests were accompanied by corresponding elastic finite element analyzes (FEA) in ABAQUS. The FEA used the material properties obtained during tensile and shear testing to define orthotropic composite plies and simulate individual printed layers in the physical specimens. Findings Experiments showed that stiffness varied by as much as 22% and failure load varied by as much as 426% between structures printed with different infill patterns. The observed failure modes were also highly dependent on infill patterns with failure propagating along with printed interfaces for all infill patterns that were consistent between layers. Elastic FEA using orthotropic composite plies was found to accurately predict the stiffness of printed structures, but a simple maximum stress failure criterion was not sufficient to predict strength. Despite this, FE stress contours proved beneficial in identifying the locations of failure in printed structures. Originality/value This study quantifies the effects of infill patterns in printed structures using a classic TO geometry. The results presented to establish a benchmark that can be used to guide the development of emerging manufacturing-oriented TO protocols that incorporate directionally-dependent, process-specific material properties.

Experimental study on the seismic performance of traditional timber mortise-tenon joints with different looseness under low-cyclic reversed loading

2018 ◽  
Vol 22 (6) ◽  
pp. 1312-1328 ◽  
Author(s):  
Jianyang Xue ◽  
Rui Guo ◽  
Liangjie Qi ◽  
Dan Xu
Keyword(s):  
Energy Dissipation ◽  
Seismic Performance ◽  
Failure Modes ◽  
Artificial Defect ◽  
Reversed Loading ◽  
Energy Dissipation Capacity ◽  
Strength And Stiffness ◽  
Seismic Behaviors ◽  
Damage Type ◽  
Better Than

The majority of existing ancient timber structures have different degrees of damage. The looseness of mortise-tenon joints is a kind of typical damage type. In order to study the influence of looseness on the seismic performance of mortise-tenon joints, six through-tenon joints and six dovetail-tenon joints with scale 1:3.2 were fabricated according to the requirements of the engineering fabrication method of Chinese Qing Dynasty. Each type of joints consisted of one intact joint and five artificial loose joints, and the artificial defect was made to simulate looseness by cutting the tenon sectional dimension. Based on experiments of two types of joints under low-cyclic reversed loading, the seismic behaviors of joints such as failure modes, hysteretic loops and skeleton curves, strength and stiffness degradation, and energy dissipation capacity were studied. Moreover, the comparative analyses of seismic performance between two types of joints were carried out. The variation tendency of seismic behaviors of two types of joints has similarities, and there are some differences due to their different structural styles. The results indicate that squeeze deformation between tenon and mortise of two types of joints occurred. The shape of hysteretic loops of two types of joints is reverse-Z-shape, and the pinching effect of hysteretic loops becomes more obvious with the increase in looseness, among which of through-tenon joints is more obvious than that of dovetail-tenon joints. The carrying capacity, stiffness, and energy dissipation capacity of loose joints are significantly lower than that of the intact one, and the energy dissipation capacity of dovetail-tenon joints is better than that of through-tenon joints. The rotation angles of two types of joints can reach 0.12 rad, and the loose joints still have great deformation capacity.

scholarly journals Experimental Study on Loading Capacity of Glued-Laminated Timber Arches Subjected to Vertical Concentrated Loads

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jiale Zhou ◽  
Chuanxi Li ◽  
Lu Ke ◽  
Jun He ◽  
Zhifeng Wang
Keyword(s):  
Cross Section ◽  
Loading Condition ◽  
Failure Modes ◽  
Loading Capacity ◽  
Concentrated Loads ◽  
Arch Models ◽  
Wood Construction ◽  
Glued Laminated Timber ◽  
Mechanical Behaviours ◽  
The Cross

Glued-laminated timber arches are widely used in gymnasiums, bridges, and roof trusses. However, studies on their mechanical behaviours and design methods are still insufficient. This paper investigates the in-plane loading capacity of circular glued-laminated timber arches made of Douglas fir. Experiments were conducted on four timber-arch models with different rise-to-span ratios under concentrated loads at mid-span and quarter-point locations. The structural responses, failure modes, and loading capacity of the timber arch specimens were obtained. The results show that the timber arches presented symmetric and antisymmetric deformation under mid-point and quarter-point loading conditions, respectively. The downward shifting of the neutral axis of the cross section was observed under mid-point loading condition, which contributes to higher loading capacity compared to that under quarter-point loading condition. The loading condition significantly affects the ultimate loads and the strain distribution in the cross section. Based on the design formula in current standards for timber structures, an equivalent beam-column method was introduced to estimate the loading capacity of the laminated timber arches under vertical concentrated loads. The moment amplification factor in the formula was compared and discussed, and the value provided in the National Design Specification for Wood Construction was recommended with acceptable accuracy.

Response of Resin Transfer Molded (RTM) Composites Under Reversed Cyclic Loading

1996 ◽  
Vol 118 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Hassan Mahfuz ◽  
Anwar Haque ◽  
Daixu Yu ◽  
Shaik Jeelani
Keyword(s):  
Failure Modes ◽  
Load Level ◽  
Failure Behavior ◽  
Progressive Damage ◽  
Damage Growth ◽  
Static Tests ◽  
Strength And Stiffness ◽  
Reversed Cyclic ◽  
Fatigue Failures ◽  
Circular Notch

Compressive behavior and the tension-compression fatigue response of resin transfer molded IM7 PW/PR 500 composite laminate with a circular notch have been studied. Fatigue damage characteristics have been investigated through the changes in the laminate strength and stiffness by gradually incrementing the fatigue cycles at a preselected load level. Progressive damage in the surface of the laminate during fatigue has been investigated using cellulose replicas. Failure mechanisms during static and cyclic tests have been identified and presented in detail. Extensive debonding of filaments and complete fiber bundle fracture accompanied by delamination were found to be responsible for fatigue failures, while fiber buckling, partial fiber fracture and delamination were characterized as the failure modes during static tests. Weibull analysis of the static, cyclic and residual tests have been performed and described in detail. Fractured as well as untested specimens were C-scanned, and the progressive damage growth during fatigue is presented. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) for the fractured specimen were also performed and the analysis of the failure behavior is presented.

Decision support systems for silviculture planning in Canada

1995 ◽  
Vol 71 (3) ◽  
pp. 291-298 ◽  
Author(s):  
William A. Thompson ◽  
Gordon F. Weetman
Keyword(s):  
Decision Support ◽  
Expert Systems ◽  
Decision Support Systems ◽  
Key Words ◽  
Support Systems ◽  
Technical Information ◽  
Telephone Interviews ◽  
Further Development

An attempt is made to identify presently available Decision Support Systems (DSS) for silviculture planning and operations. Recent sources of technical information are also identified. Based on telephone interviews, the use of and needs for silviculture DSS are outlined for eight of Canada's Model Forests. Recommendations are made for further development of DSS for Canadian silviculture. Key words: decision support systems, expert systems, silvicultural planning

Behaviour of truss plate and metal web joints in machine-stress-rated lumber trusses

1985 ◽  
Vol 12 (3) ◽  
pp. 700-716
Author(s):  
F. J. Keenan ◽  
M. M. Lepper ◽  
A. T. Quaile ◽  
E. N. Aplin
Keyword(s):  
Relative Density ◽  
Key Words ◽  
Modulus Of Elasticity ◽  
Failure Modes ◽  
Modulus Of Rupture ◽  
Design Values ◽  
Species Groups ◽  
The Mean ◽  
C 30 ◽  
Product Standard

In project A, 1500 pieces of 38 × 89 mm spruce–pine–fir lumber from three mills, in two machine-stress-rated (MSR) grades, 1650f–1.5E and 2100f–1.8E, were proof-loaded to obtain the mean modulus of elasticity, the fifth percentile modulus of elasticity, and the fifth percentile modulus of rupture. Relative density was measured for each piece, and values of the 33.3 and 52.3 percentiles of the relative density ranges were determined for each species/grade category and related to the minimum values stipulated by the National Lumber Grades Authority (NLGA) Special Product Standard SPS-2-82 for machine-stress-rated lumber. The values of relative density at the 33.3 and 52.3 percentiles that will cause the NLGA mean modulus of elasticity MOE (mean), criterion to be just barely satisfied were estimated.In project B, the lateral resistances of 480 truss plate joints were determined. The variables were two common types of truss plates (thicknesses of 0.91 mm and 1.5 mm) in two grades of MSR lumber (1650f–1.5E and 2100f–1.8E) subdivided into two species groups (pine alone and spruce–fir combined), tested at four orientations of load to grain and load to plate axis. These tests showed that, in most cases, an increase in the design capacity of truss plates in MSR lumber over the values now used for spruce–pine–fir lumber is justified.In project C, 30 commercially designed metal web floor trusses of three span/depth combinations were tested to determine their stiffnesses and strengths. Trusses with 2100f grade lumber in the chords were stiffer than the trusses with 1650f chords. In both grades, larger trusses are relatively less stiff than smaller trusses. With respect to strength, the results indicate that higher design values may be used with higher grades of MSR lumber provided that design is governed by either tooth withdrawal at the joints or by chord strength. An improved analytical model, taking into account four distinct failure modes, is required for the behaviour of floor trusses. Key words: machine-stress-rated lumber, truss plates, trusses, metal webs, strength, density.

A New Method of Reliability Analysis on Strength and Stiffness for Frame Structure

2010 ◽  
Vol 163-167 ◽  
pp. 3411-3414
Author(s):  
Yi Li ◽  
Bo Sun ◽  
Wen Zhao
Keyword(s):  
Reliability Analysis ◽  
Failure Modes ◽  
Recurrence Formula ◽  
Frame Structure ◽  
State Function ◽  
Matrix Operation ◽  
Variational Structure ◽  
Strength And Stiffness ◽  
Global Stiffness Matrix ◽  
New Criterion

An accelerating calculation of reliability analysis on strength and stiffness for frame structure was derived. The method of numerical analysis was combined with recurrence formula, to generatelimit state function of continual variational structure. This methodcan simplify the algorithm for identifying systemic dominant failure modes, because the repeated assembly of global stiffness matrix and repeated inverse matrix operation in analysis are avoided. A new criterion of degenerating the structure into mechanism is introduced. Continual analysis of variational structure can be realized.

Design of single-angle compression members according to the Canadian standards

1996 ◽  
Vol 23 (3) ◽  
pp. 632-638 ◽  
Author(s):  
Murray C. Temple
Keyword(s):  
United States ◽  
Key Words ◽  
Failure Modes ◽  
The United States ◽  
Building Codes ◽  
Flow Chart ◽  
Structural Elements ◽  
Compression Members ◽  
Principal Axes ◽  
The Many

Although single-angle compression members, attached by one leg, appear to be very simple structural elements, they are amongst the most complex of structural elements to analyze and design. This is due to the end eccentricities and the fact that the principal axes of the angle do not coincide with the axis of the structure. The design of single-angle compression members, according to the Canadian standards, is not as straightforward as might be expected. There are numerous clauses to be considered in two standards. In some cases, all failure modes are not covered explicitly. The Canadian standards are examined and applied to the two generally accepted design approaches used in Canada and the United States. These approaches are (i) to ignore the end eccentricities and to treat the angle as a concentrically loaded member and (ii) to account for the end eccentricities by treating the angle as a beam–column. A flow chart is presented which will guide the designer through the many clauses that have to be considered in the two standards. Some suggestions are made which should help a practicing engineer design single-angle compression members that are attached by one leg. Key words: angles, buckling, building (codes), design.

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