Duration of load in wood: Canadian results and implementation in reliability-based design

1993 ◽  
Vol 20 (3) ◽  
pp. 358-365 ◽  
Author(s):  
Felix Z. Yao ◽  
Ricardo O. Foschi
Keyword(s):  
Design Guidelines ◽  
Fatigue Load ◽  
Load Duration ◽  
Reliability Based Design ◽  
Theoretical Approaches ◽  
Timber Construction ◽  
Adjustment Factors ◽  
Load Effects ◽  
Accumulation Of Damage ◽  
Duration Of Load

This paper summarizes some Canadian experimental results for duration of load effects in wood, and discusses the theoretical framework utilized for their interpretation and implementation in design guidelines. The theory is based on a model for accumulation of damage, and it is used in the context of reliability assessment of a structure under load over its service life. The paper also compares results from other theoretical approaches. Finally, the background to currently recommended design adjustment factors for duration of load is discussed. Key words: fatigue, load duration, reliability, timber construction, wood.

Reliability-based design of wood structures: background to CSA-086.1-M89

1993 ◽  
Vol 20 (3) ◽  
pp. 349-357 ◽  
Author(s):  
Ricardo O. Foschi ◽  
Bryan Folz ◽  
Felix Yao
Keyword(s):  
Calibration Procedure ◽  
Code Design ◽  
Limit States ◽  
Wood Structures ◽  
Design Procedures ◽  
Reliability Based Design ◽  
Working Stress ◽  
Adjustment Factors ◽  
Duration Of Load ◽  
The Impact

The limit states design version of the 1989 Canadian code for engineering design in wood (CSA-086.1-M89) is, for the most part, reliability-based. This paper discusses the methodology employed in the calibration procedure and the reliability levels adopted. Particular emphasis is given to the results obtained for duration of load and system (load sharing) strength adjustment factors, to serviceability limit states, and to the design of columns. Final comments address the impact of the new code in comparison to the traditional working stress design procedures. Key words: code, design, reliability, timber construction, wood.

Duration of Load Effects in LRFD for Wood Construction

1991 ◽  
Vol 117 (2) ◽  
pp. 584-599 ◽  
Author(s):  
Bruce Ellingwood ◽  
David Rosowsky
Keyword(s):  
Wood Construction ◽  
Load Effects ◽  
Duration Of Load

The Development of Reliability-Based Design Guidelines and Prototype Design of Super Long-Span Bridges

2012 ◽  
Vol 18 (14) ◽  
pp. 1096-1103
Author(s):  
Ho-Kyung Kim ◽  
Myeong-Jae Lee ◽  
ByungHong Yang ◽  
Byeong-Hoon Song ◽  
HaeSung Lee ◽  
...  
Keyword(s):  
Design Guidelines ◽  
Long Span Bridges ◽  
Reliability Based Design ◽  
Long Span ◽  
Prototype Design

Fracture Mechanisms of Structural and Functional Multilayer Ceramic Structures

2011 ◽  
Vol 465 ◽  
pp. 41-46 ◽  
Author(s):  
Raúl Bermejo ◽  
Lucie Šestáková ◽  
Hannes Grünbichler ◽  
Tanja Lube ◽  
Peter Supancic ◽  
...  
Keyword(s):  
Design Guidelines ◽  
Fracture Mechanisms ◽  
Mechanical Reliability ◽  
Structural Components ◽  
Metal Electrodes ◽  
Layered Architecture ◽  
Theoretical Approaches ◽  
Metal Ceramic ◽  
Alternative Choice

The fracture of mechanically loaded ceramics is a consequence of material critical defects located either within the bulk or at the surface, resulting from the processing and/or machining and handling procedures. The size and type of these defects determine the mechanical strength of the specimens, yielding a statistically variable strength and brittle fracture which limits their use for load-bearing applications. In recent years the attempt to design bio-inspired multilayer ceramics has been proposed as an alternative choice for the design of structural components with improved fracture toughness (e.g. through energy release mechanisms such as crack branching or crack deflection) and mechanical reliability (i.e. flaw tolerant materials). This approach could be extended to complex multilayer engineering components such as piezoelectric actuators or LTCCs (consisting of an interdigitated layered structure of ceramic layers and thin metal electrodes) in order to enhance their performance functionality as well as ensuring mechanical reliability. In this work the fracture mechanisms in several structural and functional multilayer components are investigated in order to understand the role of the microstructure and layered architecture (e.g. metal-ceramic or ceramic-ceramic) on their mechanical behaviour. Design guidelines based on experiments and theoretical approaches are given aiming to enhance the reliability of multilayer components.

Duration of load effects in lumber. Part I: A fracture mechanics approach

1982 ◽  
Vol 9 (3) ◽  
pp. 502-514 ◽  
Author(s):  
Kenneth Johns ◽  
Borg Madsen
Keyword(s):  
Fracture Mechanics ◽  
Stress Ratio ◽  
Failure Time ◽  
Creep Function ◽  
Load Effect ◽  
Mechanics Model ◽  
Current Design ◽  
Load Effects ◽  
Duration Of Load

In Part I of this paper, the deterioration of the strength of lumber with continued application of constant stress, called the duration-of-load effect, is treated using a viscoelastic, limited ductility fracture mechanics model. The model is explained and developed in a general way, then modified for use with commercial lumber. The problems of assigning correct creep function parameters and values of stress ratio for use in calculations involving the model are discussed. The evident weakening of boards surviving a long-term test can be used to project a failure time that is longer than the test period. Numerical results are shown and compared with the Madison curve, the basis for current design codes. Parts II and III of this paper demonstrate experimental verification and discuss design implications.

Floor vibration due to occupants and reliability-based design guidelines

1995 ◽  
Vol 22 (3) ◽  
pp. 471-479 ◽  
Author(s):  
Ricardo O. Foschi ◽  
Greg A. Neumann ◽  
Felix Yao ◽  
Bryan Folz
Keyword(s):  
Close Agreement ◽  
Analytical Study ◽  
Coupled System ◽  
Design Guidelines ◽  
Vibrational Response ◽  
Reliability Based Design ◽  
Floor Vibration ◽  
Coupled Dynamical System ◽  
Commercial Applications ◽  
Acceptability Criteria

Lightweight floors for residential or commercial applications may exhibit annoying levels of vibration under occupancy loading. This paper presents an experimental and analytical study of the vibrational response of wood floors to impact produced by occupants. The results show that, for the analysis of this type of floors, it is necessary to consider the coupled dynamical system of floor and occupants. It is also shown that occupants may be modelled with simple oscillators, and that the dynamic analysis of the coupled system can produce close agreement with tests. Acceptability criteria are used to study design guidelines, combining the variability in floor stiffness with the variability in human tolerance to vibrations. Floors considered use 2 × 8 SPF joists and I-joists. Key words: vibrations, serviceability, occupancy loads, wood floors, reliability.

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