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Introduction
Published in Burt G. Look, Earthworks, 2023
Both the recent site history and geological history should be understood (Figure 1.4-3). The time scales demand special mention as geological stability cannot be assured, and the life of any earth structure earth must be considered part of the design. Maintenance is also required during its design life. Soils formed in the Holocene epoch have a different structure than for any other geological time.
Design for Reliability Process
Published in Ali J Jamnia, Khaled Atua, Executing Design for Reliability within the Product Life Cycle, 2019
Often, life expectancy is equated with design life. Design life is defined as the length of time during which a product/system/component is expected to operate within its specifications. However, this definition appears to suggest that failures do not happen at all, though this is not always the case. It should be clarified that reliability is among the specifications within which the design is expected to operate. Reliability, as a specification of the design, can be defined in terms of mean time between failure (MTBF), or failure rate. So for a given design, the reliability specification assumes that failure will occur during the design life or life expectancy at a certain acceptable limit. For this reason, we will define the design life as the length of time that a product/system/component operates within its expected failure rate and/or expected reliability target. For example, a repairable product may have the reliability specification set as no greater than 1% monthly failure rate over a design life or life expectancy of 10 years. This implies that for a period of 10 years, on average 1% of the product population fails every month. If consumers or end users operate this product beyond 10 years, the OEM should expect to see an increase in the monthly frequency of the reported failures of the product.
FRP strengthening of concrete structures using AS5100-2017
Published in Nigel Powers, Dan M. Frangopol, Riadh Al-Mahaidi, Colin Caprani, Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges, 2018
While a 30 year design life is mentioned in the standard, a longer design life can be achieved and ensured by routine inspections and maintenance. FRP system can be repaired relatively easily using techniques as outlined in Pham (2009) and TR 57 Report.
Availability-based predictive maintenance scheduling for vibrating-grate biomass boilers
Published in Safety and Reliability, 2020
Mohammad Hosseini Rahdar, Fuzhan Nasiri, Bruno Lee
The maintenance efforts on actual or upcoming failure are ideally predicted to preserve components and systems keep running efficiently for design life or more. For most of the equipment, periodic maintenance is required to guarantee the design life assigned by the product’s manufacturers. Hence, in the course of failing to fulfil the maintenance activities determined by the designers, it would not be surprising to shorten the equipment life. Industrial and process plants generally utilise two modes of maintenance programme (Keith Mobley, 2004; Senge, 2004; Sutton, 2017; U.S. Department of Energy, 2010); the first mode is called run-to-failure and the second one is preventive maintenance management which this paper will focus on this method.
Long-span bridges: analysis of trends using a global database
Published in Structure and Infrastructure Engineering, 2020
Colin C. Caprani, James De Maria
The concept and definition of ‘design life’, various across international standards and is closely related with the concept of ‘service life’. The relevant definitions for some international codes are: AASHTO (2012) LRFDDesign life: the ‘period of time on which the statistical derivation of transient loads is based’.Service life: ‘the period of time that the bridge is expected to be in operation’.EN 1990.2002:Design working life: the ‘assumed period for which a structure or part of it is to be used for its intended purpose with anticipated maintenance but without major repair being necessary’.Reference period: the ‘chosen period of time that is used as a basis for assessing statistically variable actions, and possibly for accidental actions’.AS5100.1-2004: Design life: ‘the period assumed in design for which a structure or structural element is required to perform its intended purpose without replacement or major structural repairs’.Service life: ‘a period over which a structure element is expected to perform its function without major maintenance or structural repair’.