The enhanced performance of split-ring connections through prestressing

1991 ◽  
Vol 18 (5) ◽  
pp. 830-838 ◽  
Author(s):  
J. H. P. Quenneville ◽  
K. Van Dalen
Keyword(s):  
Key Words ◽  
Engineering Design ◽  
Laboratory Study ◽  
Laboratory Tests ◽  
Simple Technique ◽  
Douglas Fir ◽  
Limit States ◽  
Split Ring ◽  
Lap Splices

This paper examines the concept of enhancing the performance of timber connectors in truss joints by the introduction of transverse prestressing. The behaviour of lap splices of Douglas fir, with 63 mm split-ring connectors and end distances of 50, 100, 150, and 210 mm, was examined for various levels of prestress in a laboratory study. As well, the magnitude of the load that can be carried by the connection through friction between faying surfaces was also assessed for various levels of prestress. The simple technique used in the laboratory for introducing prestress is described. Results of the laboratory tests on 20 joint configurations are presented, and the experimentally determined strengths are compared with the calculated resistances using the provisions of CAN\CSA-086.1-M89 "Engineering design in wood (limit states design)." Key words: timber, connector, prestress, truss joint.

Combined effects of end distance and spacing on the resistance of split ring connectors loaded in tension

1994 ◽  
Vol 21 (5) ◽  
pp. 789-796 ◽  
Author(s):  
A. Charron ◽  
P. Quenneville
Keyword(s):  
Experimental Study ◽  
Key Words ◽  
Engineering Design ◽  
Linear Relation ◽  
Combined Effects ◽  
Split Ring ◽  
Design Standard ◽  
Design Philosophy ◽  
End Distance

An experimental study was undertaken to verify the combined effects of timber connector end distance and spacing requirements of the Canadian standard for engineering design in wood. A total of 130 test specimens using 63 mm diameter split rings were loaded to failure in tension. The split ring end distance varied between 50 and 210 mm and the spacing varied between 80 and 200 mm. Results show that a linear relation exists between the connector end distance and its resistance for a given spacing. Increase in spacing also results in an increase of the connector resistance for a given end distance. Also, connections with two connectors in a row can resist significant loads even if the end distance or spacing of one connector is below the standard minimum required value. Thus, the design philosophy of Clause 10.3.3 of the wood design standard is inadequate for these joints. Key words: split ring, tension, end distance, spacing, resistance, timber.

Effect of end distance on the resistance of split ring connectors in timber joints loaded in compression

1993 ◽  
Vol 20 (5) ◽  
pp. 863-871 ◽  
Author(s):  
Pierre Quenneville ◽  
Alain Charron ◽  
Karl Van Dalen
Keyword(s):  
Engineering Design ◽  
Species Group ◽  
Douglas Fir ◽  
Experimental Program ◽  
Split Ring ◽  
Ring Compression ◽  
Larch Species ◽  
Cleavage Strength ◽  
End Distance ◽  
Timber Joints

An experimental program was undertaken to verify the end distance requirements in the Canadian standard for engineering design in wood for split ring connectors in joints loaded in compression. In a laboratory study, 48 joints of the Douglas fir-larch species group using 63 mm diameter split rings, 45 joints of the Douglas fir-larch species group using 102 mm diameter split rings, and 51 joints of the spruce-pine-fir species group using 63 mm diameter split rings were loaded to failure in compression. The split ring end distance varied between 50 and 200 mm for joints with 63 mm diameter split rings and between 80 and 220 mm for joints with 102 mm diameter split rings. Tests were also carried out to verify the cleavage strength of the wood and the strength of the wood in compression parallel-to-grain for each of the specimens. Results show that the end distance does not have any significant effect on the resistance of split ring connectors in joints with members loaded in compression. Key words: split ring, compression, end distance, timber, resistance.

Effect of end distance on the resistance of spilt ring and shear plate connectors loaded perpendicular to grain

1996 ◽  
Vol 23 (5) ◽  
pp. 989-997
Author(s):  
J. H. P. Quenneville ◽  
J. G. A. Charron
Keyword(s):  
Experimental Study ◽  
Species Group ◽  
Douglas Fir ◽  
The Other ◽  
Limit States ◽  
Split Ring ◽  
Ring Shear ◽  
Shear Plate ◽  
Larch Species ◽  
End Distance

An experimental study was undertaken to verify the end distance requirements in the CSA Standard O86.1-94 "Engineering design in wood (limit states design)" for split ring and shear plate connectors in joints loaded perpendicular to grain. In a laboratory study, 48 joints of the Douglas fir – larch species group were loaded to failure perpendicular to grain. Twenty-eight of those joints were tested using 102 mm diameter shear plates, and the remaining 20 joints were tested using 63 mm diameter split rings. Of the 28 joints tested with 102 mm shear plates, 16 of the specimens were made of laminated Douglas fir and the other 12 specimens were made of sawn lumber Douglas fir. End distances of 80, 130, 140, and 180 mm were studied for each of the two shear plate tests. Specimens using 63 mm split rings were tested at end distances of 80 and 140 mm. Results show that when using 102 mm shear plate and 63 mm split ring connectors, the end distance of the connector has no statistically significant effect on the resistance of the connector. Changes to the Canadian wood design standard are recommended. Key words: wood, fasteners, resistance, split ring, shear plate, end distance.

scholarly journals Cost of pruning Douglas-fir in coastal British Columbia

1994 ◽  
Vol 70 (1) ◽  
pp. 80-83
Author(s):  
S. A. Y. Omule ◽  
D. E. Paul ◽  
L. M. Darling
Keyword(s):  
British Columbia ◽  
Key Words ◽  
Travel Time ◽  
Douglas Fir ◽  
Time Study ◽  
Average Spacing ◽  
The Cost ◽  
Coastal British Columbia

Artificial pruning can increase the quantity of high-value clear lumber harvested from Douglas-fir, but the pruning cost per tree is relatively high. To prune a young Douglas-fir to 6 metres in one lift and two lifts took, respectively, 9.5 and 10.1 minutes in 14- and 18-year old stands with average spacing between trees of about 3 metres on flat or 0-30% south-facing slopes in coastal British Columbia. The associated costs were $2.09 and $2.22. This included minor travel time between trees, but excluded the cost of travelling to the site, selecting and marking trees to be pruned, and purchasing and maintaining the pruning equipment. Differences in pruning time between one-lift pruning and two-lift pruning, in one or two passes, were small. A D-handled saw was preferred to the more strenuous snap-cut pruner with ratchet-style pinions, based on observations on a pruning time-study of 5 operators. Key words: pruning saw, snap-cut pruner, pruning time, one-lift pruning, two-lift pruning

DISPERSION OF KAOLINITE BY WATER EXTRACTS OF DOUGLAS-FIR ASH

1984 ◽  
Vol 64 (3) ◽  
pp. 439-443 ◽  
Author(s):  
PHILIP B. DURGIN ◽  
PHILIP J. VOGELSANG
Keyword(s):  
Key Words ◽  
Chemical Constituents ◽  
Douglas Fir ◽  
Specific Adsorption ◽  
Water Extracts ◽  
Inorganic Constituents

The inorganic constituents of black and gray ash from Douglas-fir slash were analyzed to evaluate the mechanism by which ash extract disperses kaolinite. Chemical constituents promoting kaolinite dispersion were anions that increase alkalinity and are specifically adsorbed, namely orthophosphate, carbonate, hydroxyl, and me-tasilicate. Key words: Fire, specific adsorption, carbonate

scholarly journals A new concept of upflow clarification in activated sludge separation

1986 ◽  
Vol 13 (5) ◽  
pp. 517-522
Author(s):  
Arthur B. Sparling ◽  
David L. Woytowich
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Activated Sludge ◽  
Key Words ◽  
Laboratory Study ◽  
Removal Mechanism ◽  
Operating Characteristics ◽  
Activated Sludge System ◽  
Gravity Sedimentation ◽  
Settling Characteristics

An experimental investigation was conducted to evaluate a new concept of upflow clarification. A novel sludge removal mechanism that used the entire floor area for the removal of solids was incorporated in an upflow clarifier. The operating characteristics and design features of the continuous flux upflow clarifier (CFLUC) are described in detail. The laboratory study was conducted to determine the effectiveness of the CFLUC clarifier in separating sludges with different settling characteristics. The different sludge types were produced by an activated sludge system treating a synthetic dairy waste at four different food to microorganism (F: M) ratios. At low organic loadings (0.10–0.24 (g COD)(g MLVSS)−1 (d)−1), the CFLUC clarifier removed 70% of the pinpoint floe that remained during quiescent batch settling conditions. At high organic loadings (0.41–0.83 (g COD)(g MLVSS) −1 (d) −1), the CFLUC clarifier was capable of separating filamentous bulking sludges with poor settling characteristics. Based on the results of the experimental study the upflow clarifier effectively separated all sludge types over the range of organic loadings investigated. Key words: CFLUC clarifier, secondary clarification, upflow clarification, sludge blanket, bioflocculation, bulking sludge, gravity sedimentation.

Factors influencing formwork productivity

1993 ◽  
Vol 20 (1) ◽  
pp. 144-153 ◽  
Author(s):  
Gary R. Smith ◽  
Awad S. Hanna
Keyword(s):  
Key Words ◽  
Engineering Design ◽  
Work Hours ◽  
Daily Output ◽  
Daily Work ◽  
Construction Methods ◽  
Productivity Data ◽  
Factors Influencing ◽  
Measurable Factors

Estimates indicate that 30 to 70 percent of cast-in-place concrete cost is attributable to the assembly and stripping of formwork. This wide percentage range is partially due to factors that are not well understood with regard to their influence on productivity. The purpose of this paper is to identify the factors that influence formwork productivity and identify a methodology to evaluate productivity data. Two groups of factors were found to have a great effect on formwork productivity: non-measurable factors such as contract document and measurable factors such as engineering design. This paper discusses the effect of both groups of factors on the productivity of vertical formwork. To quantify the effect of the measurable factors on formwork productivity, a case study of the productivity of a crew of carpenters erecting wall formwork for a three-story underground parking structure is presented and analyzed. Data were collected by physically measuring the daily output of vertical formwork erected and the total daily work hours. Key words: formwork, productivity, construction methods.

Étude en laboratoire de l'adhérence béton de resurfaçage - dalle de chaussée

1992 ◽  
Vol 19 (6) ◽  
pp. 1041-1048
Author(s):  
Minh-Tan Do ◽  
Gilles Chanvillard ◽  
Claude Lupien ◽  
Pierre-Claude Aïtcin
Keyword(s):  
Key Words ◽  
Elastic Foundation ◽  
Laboratory Study ◽  
Shear Test ◽  
Bonding Agent ◽  
Bonding Agents ◽  
Test Setup ◽  
Slab Temperature ◽  
Flexure Test ◽  
Slant Shear

This paper presents a laboratory study on the bonding of a concrete overlay to an old slab. The main variables of the study were the bonding agents and the initial slab temperature when the overlay was placed. A flexure test setup, based on the theory of beams of elastic foundation, was developed. The results obtained were compared with those of the slant–shear test. Key words: bonding agent, debonding, elastic foundation, interface, beam.

Résultats d'essais sur des assemblages soudés excentriques en flexion

1985 ◽  
Vol 12 (3) ◽  
pp. 494-506 ◽  
Author(s):  
D. Beaulieu ◽  
A. Picard
Keyword(s):  
Laboratory Tests ◽  
Load Application ◽  
Deformation Characteristics ◽  
Limit States ◽  
Fillet Weld ◽  
Center Of Rotation ◽  
Actual Load ◽  
Simplifying Assumptions ◽  
Instantaneous Center ◽  
Work Done

The development, by Butler and Kulak, of equations for the calculation of fillet weld resistance with relation to the angle of load application has improved the understanding of the limit states behavior of welded connections. For the design of welded connections subjected to shear and moment, Dawe and Kulak developed a method of analysis based on the principle of instantaneous center of rotation, which accounts for the actual load–deformation characteristics of the weld. Due to its complexity, the method of Dawe and Kulak requires the use of a computer. In order to make the method more attractive to the designer, Neis suggested some simplifying assumptions and at the same time criticized the work done by Dawe and Kulak. In the discussions that followed the publication of his results, various researchers expressed diverging opinions on several matters related to the theories.Since the proposed methods were based on the results of only 8 laboratory tests done by Dawe and Kulak, we have carried out a series of 24 tests. The results of these tests were compared with the theoretical ultimate loads obtained from the methods of Dawe and Kulak and Neis, and demonstrate that the proposed methods are adequate as long as they are used within certain limits and respect certain conditions.

Platelet storage solution effects on the accuracy of laboratory tests for platelet function: a multi-laboratory study

Vox Sanguinis ◽  
2004 ◽  
Vol 86 (3) ◽  
pp. 183-188 ◽  
Author(s):  
T. VandenBroeke ◽  
L. J. Dumont ◽  
S. Hunter ◽  
J. Nixon ◽  
S. Murphy ◽  
...  
Keyword(s):  
Platelet Function ◽  
Laboratory Study ◽  
Laboratory Tests ◽  
Platelet Storage ◽  
Storage Solution
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