Effect of long-term loading on timber load-bearing elements

2015 ◽  
Vol 10 (2) ◽  
pp. 25-34
Author(s):  
Kristian Sogel
Keyword(s):  
Load Bearing

EXPERIMENTAL INVESTIGATION OF THE DURABILITY OF LOAD BEARING TIMBER-GLASS COMPOSITES UNDER THE EFFECTS OF ACCELERATED AGING

2019 ◽  
Vol 14 (2) ◽  
pp. 45-59 ◽  
Author(s):  
Halet Almila Arda Buyuktaskin ◽  
Mehmet Serkan Yatagan ◽  
Gulseren Erol Soyoz ◽  
Leyla Tanacan ◽  
Morvarid Dilmaghani
Keyword(s):  
Raw Materials ◽  
Accelerated Aging ◽  
Structural Elements ◽  
Atmospheric Conditions ◽  
Aging Effects ◽  
Glass Composite ◽  
Load Bearing ◽  
Glass Composites ◽  
Before And After

Although timber was used extensively as a structural material for traditional buildings in Turkey in the past, usage of structural timber decreased significantly over time and timber has been largely replaced by other materials. As timber is a natural, durable and sustainable material, it would be desirable to re-introduce timber structural elements to contemporary construction in a form that is appealing to industry. Timber-glass composite structural elements are potentially a good candidate for this purpose. To that end, a series of tests were conducted on load-bearing timber-glass composites in order to understand the long–term structural performance of the composite material under atmospheric conditions; to decrease the recurring cost of repair and maintenance; and to minimize the exhaustion of raw materials and energy. In this paper, the first part of this experimental work is presented, which focuses on the durability of timber-glass composite under the effects of accelerated aging, carried out on small-sized timber-glass composite specimens. Accelerated aging effects were observed under wetting-drying, freezing-thawing, UV effects, resistance to acids and high temperature. The mechanical strength of the timber-glass composite specimens before and after the effect of accelerated aging was measured by adhesion and shear strength tests and a comparative analysis of the results was carried out. The results of the experiments indicate that timber-glass composite is suitable to be used under protection from environmental conditions.

scholarly journals Engineering diagnostics of shaft lining in Gubkin Mine

2020 ◽  
pp. 64-67
Author(s):  
S. V. Sergeev ◽  
◽  
E. D. Vorobiev ◽  
I. M. Ignatenko ◽  
A. V. Zinchenko ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Field Studies ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Mine Dumps ◽  
Design Values ◽  
Engineering Diagnostics ◽  
Shaft Lining ◽  
Compression Resistance

Shafts in Gubkin Mine, KMAruda have been in operation since the late 1940s. The shafts are sunk in difficult hydrogeological conditions. At the present time, due to transition to deeper levels, deeper mine dumps are required. It is necessary to reinforce shaft lining in watered rocks. During long-term service of shaft 1, due to corrosion, thickness of liner plates and horizontal ribs has decreased by 1.5–2 and 3–5 mm, respectively (two-side corrosion). As a result, the load-bearing capacity of the tubbing has lowered by 5–7%. At the same time, the actual stresses are not higher than 22 MPa, which is 10 times less than the design compression resistance of gray cast iron as per Construction Code SP 16.13330.2017. Field studies have been performed in Gubkin Mine toward improvement of operating safety of shafts during mineral mining at deeper levels. Stress state diagnostics of lining in shaft 1 shows that the lining preserves its load-bearing capacity in all types of rocks. Thus, safe operation can be continued without extra expenses connected with the lining reinforcement. The field studies in the cage shaft show that pressure on the lining in frozen rocks is 1.5–2 times higher than the design values. It is recommended to continue the studies to estimate effects of possible rock displacements on the lining during further mining.

Triple Arthrodesis: A Long-term Study with Force Plate Analysis

Foot & Ankle ◽  
1981 ◽  
Vol 2 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Richard B. Southwell ◽  
Frederick C. Sherman
Keyword(s):  
Normal Load ◽  
Force Plate ◽  
Varus Deformity ◽  
Triple Arthrodesis ◽  
Load Bearing ◽  
Long Term Study ◽  
Clinical Methods ◽  
Plate Analysis

This study evaluated triple arthrodesis at late follow-up using the liquid crystal force plate and standard clinical methods. Twenty-four patients with 36 triple arthrodeses were followed-up at an average of 8 ± 2 years. Fifty-eight per cent of patients achieved an ideal or good rating with 11% failures. Failures were due to inadequate surgical correction of varus deformity. Seven per cent of joints with roentgenographic degenerative changes had associated mild pain. Triple arthrodesis produced many deviations from normal load-bearing: 1) calcaneovalgus residuals produced symptomatic posterior heel force concentrations; 2) residual forefoot supination produced symptomatic force concentrations under the fifth metatarsal and toe; 3) residual forefoot pronation produced increased midfoot and medial metatarsal load-bearing, generally asymptomatic; and 3) a significant increase in midfoot weightbearing occurred in most triple arthrodesis patients.

The Bone-Biomaterial Interface for Load-Bearing Implants

MRS Bulletin ◽  
1991 ◽  
Vol 16 (9) ◽  
pp. 55-61 ◽  
Author(s):  
R.M. Pilliar ◽  
J.E. Davies ◽  
D.C. Smith
Keyword(s):  
Fibrous Tissue ◽  
Orthopedic Implants ◽  
Minimal Risk ◽  
Implant Fixation ◽  
Load Bearing ◽  
Joint Replacements ◽  
Surgical Implants ◽  
Equal Importance ◽  
Order Of Magnitude

Bone-interfacing surgical implants used in orthopedics and dentistry must bear the forces of normal patient activity with minimal risk of mechanical failure of the implant. This requires using appropriate materials and designs for implant fabrication. Additionally, reliable long-term implant attachment to host bone must be assured so that effective force transfer between implant and bone occurs for the patient's lifetime without the implant loosening. With recent advances in implant designs and techniques for their placement, effective implant fixation to bone can last for years (decades) either directly or through an acceptable intermediate fibrous tissue layer at the bone-implant interface. With approximately 500,000 artificial hips implanted annually worldwide and the demand for other joint replacements approaching the same order of magnitude, as well as the recent major growth in the use of dental implants (300,300 projected for insertion in North America alone in 1991), the assurance of effective implant-to-bone fixation is extremely important.Studies of implant biocompatibility have resulted from concerns over the cumulative effects of foreign element release through implant corrosion and wear. Accumulation of this debris in tissues both local and remote to implant sites over the long term is a concern. Of equal importance, for load-bearing implants, are studies to determine the important factors for successful long-term implant fixation. Current trends in design and use of both dental and orthopedic implants reflect the trial-and-error approach that has characterized this field for decades.

scholarly journals Assessment of load bearing clay brick masonry for analyzing long-term durability through field measurement and visual review

2021 ◽  
Author(s):  
Blair E. Williams
Keyword(s):  
Three Dimensional ◽  
Brick Masonry ◽  
Clay Brick ◽  
Saturation Point ◽  
Load Bearing ◽  
Freeze Thaw ◽  
Uniform Manner ◽  
Mosaic Images

This thesis examines a load bearing clay brick century home research house in Toronto (Canada) which has recently undergone the addition of polyurethane foam insulation on all interior sides of the exterior clay brick load bearing walls, increasing the insulating value in areas to RSI 7.9 W/m2K, on average. This study introduces and advances techniques to create high-resolution stitched mosaic images of the elevations to visually document the current physical condition of the brick. The critical saturation point was used to determine the capabilities of the clay brick masonry to resist freeze-thaw damage by way of frost dilatometry testing and compared to measurements taken by in-situ moisture content sensors in the brick masonry. This project also reveals how bricks expand and deteriorate in non-uniform manner during saturated three-dimensional dilatometry testing.

scholarly journals Prevention of uncontrolled progressive collapse of a high-rise brick building

2018 ◽  
Vol 143 ◽  
pp. 01006
Author(s):  
Oleg Pakhmurin
Keyword(s):  
Climatic Factors ◽  
Progressive Collapse ◽  
Operational Reliability ◽  
Structural Elements ◽  
Load Bearing ◽  
Term Operation ◽  
High Rise ◽  
Failure Diagram ◽  
Stone Walls

In recent years, there is a trend towards increasing the failure rate of buildings and structures as a result of unforeseen situations. This study is aimed at assessing the operational reliability of the structure to prevent emergencies and progressive collapse. The behavior of structures affected by various factors was analyzed. The operational condition of a building with stone walls and a rigid structural frame constructed in the middle of the 20th century was considered. By means of a detailed instrumental examination, effects of long-term operation, climatic factors and violations during construction on the serviceability of the building were analyzed. Geotechnical conditions of the site were investigated. Necessary re-calculations for load-bearing structural elements and foundations were carried out. An expected failure diagram for vertical load-bearing structures of the building is presented. Proposals for preventing progressive collapse were developed on the basis of the author's technique.

scholarly journals Test Loading of Structures with a Suspect Resistance

2021 ◽  
Vol 11 (8) ◽  
pp. 3424
Author(s):  
Tuomo Poutanen ◽  
Sampsa Pursiainen ◽  
Jari Mäkinen
Keyword(s):  
Service Time ◽  
Point Of View ◽  
Theoretical Point ◽  
Test Load ◽  
Load Bearing ◽  
Special Cases ◽  
Significant Research ◽  
Research Questions ◽  
Test Loading

The reliability of load-bearing structures is normally secured through codes, a competent structural design and proper execution inspection. Alternatively, the reliability can be obtained via skilled test loading, which is a feasible technique both in the construction of new structures and in the load-bearing verification of existing ones. Although the current codes lack instructions for test loading, they are, however, used in special cases; for example, when the reliability of the structures is doubtful due to a defect, or when the structure is suspected to have especially high resistance variability. Test loading involves significant research questions that need to be addressed, including: What is the test load in comparison with the expected maximum service time load or the characteristic load? How can the instantaneous test load be compared with the actual long-term service-time load? Does the test loading harm the structure, and what is the target reliability in the test loading calculation? In this paper, we approach these questions from a theoretical point of view and propose how a suitable test load can be chosen in practice using an approximate and a precise approach.

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