The endurance time (ET) method is a dynamic structural analysis procedure for seismic assessment of structures. In this procedure, an intensifying dynamic excitation is used as the loading function. [1] Endurance time method is a time-history based dynamic analysis procedure. An estimate of the structural response at different equivalent seismic intensity levels is obtained in a single response history analysis. [2] This method has applications in seismic assessment of various structural types and in different areas of earthquake engineering. [3] [4] [5]
Endurance time (ET) method is a dynamic structural analysis procedure in which intensifying dynamic excitation is used as the loading function. An estimate of structural response and/or performance at the entire seismic intensity range of interest is obtained in each response history analysis. The concept of endurance time analysis is similar to the exercise test applied in medicine. [6] Similar concept has also been extended to applications in the analysis of offshore platforms under water waves. [7]
The basic concepts of the endurance time method were published in 2004. [8] Application in linear seismic analysis appeared in 2007. [2] ET was subsequently extended to nonlinear analysis of single degree of freedom (SDOF) and multi degree of freedom systems. [9] Procedures for multi-component seismic analysis were subsequently developed. [10] [11] [12] [13]
ET excitation functions are generated by using numerical optimization methods. [14] [15] ET excitation functions are publicly available through internet websites. [1] [16] ET excitation functions can be categorized into five generations as follows:
Endurance time method has been applied in the following areas of earthquake engineering:
ET method has been applied in seismic assessment of the following structural types:
Major advantages of the endurance time method are as follows:
Major limitations of the endurance time method are as follows:
In metallurgy, a shape-memory alloy (SMA) is an alloy that can be deformed when cold but returns to its pre-deformed ("remembered") shape when heated. It is also known in other names such as memory metal, memory alloy, smart metal, smart alloy, and muscle wire. The "memorized geometry" can be modified by fixating the desired geometry and subjecting it to a thermal treatment, for example a wire can be taught to memorize the shape of a coil spring.
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codes in the late 1960s for developed countries and late 1970s for many other parts of the world, many structures were designed without adequate detailing and reinforcement for seismic protection. In view of the imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world – such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines. These codes must be regularly updated; the 1994 Northridge earthquake brought to light the brittleness of welded steel frames, for example.
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Cross-laminated timber (CLT) is a subcategory of engineered wood with panel product made from gluing together at least three layers of solid-sawn lumber. Each layer of boards is usually oriented perpendicular to adjacent layers and glued on the wide faces of each board, usually in a symmetric way so that the outer layers have the same orientation. An odd number of layers is most common, but there are configurations with even numbers as well. Regular timber is an anisotropic material, meaning that the physical properties change depending on the direction at which the force is applied. By gluing layers of wood at right angles, the panel is able to achieve better structural rigidity in both directions. It is similar to plywood but with distinctively thicker laminations.
Scientia Iranica is a peer-reviewed scientific journal published by Sharif University of Technology. It was established in 1991 and covers theoretical and experimental research in technical sciences and engineering. Starting in 2011, the journal is published open access. The editor-in-chief is Abolhassan Vafai.
Carbon fiber-reinforced polymers, carbon-fibre-reinforced polymers, carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic, also known as carbon fiber, carbon composite, or just carbon, are extremely strong and light fiber-reinforced plastics that contain carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications.
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A buckling-restrained brace (BRB) is a structural brace in a building, designed to allow the building to withstand cyclical lateral loadings, typically earthquake-induced loading. It consists of a slender steel core, a concrete casing designed to continuously support the core and prevent buckling under axial compression, and an interface region that prevents undesired interactions between the two. Braced frames that use BRBs – known as buckling-restrained braced frames, or BRBFs – have significant advantages over typical braced frames.
Mete Avni Sözen was Kettelhut Distinguished Professor of Structural Engineering at Purdue University, Indiana, United States from 1992 to 2018.
Vibration fatigue is a mechanical engineering term describing material fatigue, caused by forced vibration of random nature. An excited structure responds according to its natural-dynamics modes, which results in a dynamic stress load in the material points. The process of material fatigue is thus governed largely by the shape of the excitation profile and the response it produces. As the profiles of excitation and response are preferably analyzed in the frequency domain it is practical to use fatigue life evaluation methods, that can operate on the data in frequency-domain, s power spectral density (PSD).
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Medhat Haroun was an Egyptian-American expert on earthquake engineering. He wrote more than 300 technical papers and received the Charles Martin Duke Lifeline Earthquake Engineering Award (2006) and the Walter Huber Civil Engineering Research Prize (1992) from the American Society of Civil Engineers.
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This glossary of structural engineering terms pertains specifically to structural engineering and its sub-disciplines. Please see glossary of engineering for a broad overview of the major concepts of engineering.
Pres-Lam is a method of mass engineered timber construction that uses high strength unbonded steel cables or bars to create connections between timber beams and columns or columns and walls and their foundations. As a prestressed structure the steel cables clamp members together creating connections which are stronger and more compact than traditional timber fastening systems. In earthquake zones, the steel cables can be coupled with internal or external steel reinforcing which provide additional strength and energy dissipation creating a damage avoiding structural system.
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