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1. Seismic performance assessment of conventional construction concrete moment-resisting frame buildings in Canada using the FEMA P695 methodology

Author

Fazileh, Farrokh, Khosravi, Sadegh, Dolati, Abouzar, Fathi-Fazl, Reza, and Saatcioglu, Murat

Subjects
Government regulation, Earthquake engineering, Building -- Laws, regulations and rules, Engineering research, Earthquake resistant design
Abstract

National Building Code of Canada (NBC) specifies 45 Seismic Force Resisting Systems to ensure the safety of building structures. Conventional construction concrete moment-resisting frame (CC-CMF) is one of these systems whose seismic response has not been systematically studied in Canada. This paper is an attempt to study the seismic performance of this system using the FEMA P695 methodology. In this regard, different archetype configurations were developed and analyzed through nonlinear static and dynamic analyses. Performance assessment results show that the CSA and NBC requirements for CC-CMF system represent the lower bound of values for seismic force modification factors, and conservatively meet life safety objectives presented in the NBC. Furthermore, different scenarios were considered for identifying ductility-related seismic force modification factor from pushover curves. The effect of height and gravity load levels on seismic force modification factors and collapse margin ratios are also presented by comparing archetypes having different configurations. Keywords: conventional construction concrete moment-resisting frames, seismic performance assessment, seismic force modification factors, seismic design requirements, collapse margin ratio Le Code national du batiment du Canada (CNB) precise 45 systemes de resistance sismique pour assurer la securite des charpentes de batiment. Les ossatures resistant au moment de construction classique (<< CC-CMF >>) constituent l&apos;un de ces systemes dont la reponse sismique n&apos;a pas ete systematiquement etudiee au Canada. Dans le cadre de cet article, on tente d&apos;etudier les performances sismiques de ce systeme en utilisant la methodologie FEMA P695. A cet egard, differentes configurations d&apos;archetype ont ete elaborees et examinees au moyen d&apos;analyses statiques et dynamiques non lineaires. Les resultats de l&apos;evaluation de la performance montrent que les exigences de la CSA et du CNB pour le systeme CC-CMF representent la limite inferieure des valeurs pour les facteurs de modification des forces sismiques, et respectent de facon prudente les objectifs de securite des personnes presentes dans le CNB. En outre, differents scenarios ont ete envisages pour determiner le facteur de modification de la force sismique lie a la ductilite a partir des courbes de poussee (<< pushover curves >>). L&apos;effet de la hauteur et des niveaux de charge de gravite sur les facteurs de modification des forces sismiques et les rapports de marge d&apos;affaissement est egalement presente en comparant des archetypes ayant des configurations differentes. [Traduit par la Redaction] Mots-cles : ossatures resistant au moment de construction classique, evaluation de la performance sismique, facteurs de modification de la force sismique, exigences de conception sismique, rapport de marge d&apos;affaissement, 1. Introduction The National Building Code of Canada (NBC 2015a) includes 45 different seismic force resisting systems (SFRSs) applicable to a wide range of seismicity levels and building configurations. Concrete [...]

Published
2022
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2. Seismic Retrofit of Reinforced Concrete Frame Buildings with Tension Only Braces

Author

Khosravi, Sadegh

Subjects
concrete frames, PEC, cables, bracing, drift control, seismic design, shape memory alloys (SMA), earthquake engineering, ductility, progressively engaging braces, seismic retrofit, braces
Abstract

Reinforced concrete buildings built prior to the enactment of modern seismic codes are often seismically deficient. These buildings may have inadequate strength and ductility to withstand strong earthquakes. Conventional retrofit techniques for such frame buildings involve adding reinforced concrete shear walls or structural bracing systems to the existing bays. These techniques can be intrusive and result in lengthy down times and expensive structural interventions. An alternative to conventional techniques is the use of high-strength prestressing strands or cables, diagonally placed as tension elements. This technique was researched and used in a limited manner after the 1985 Mexico City Earthquake. It has since been further investigated at the University of Ottawa through experimental and analytical research (Shalouf and Saatcioglu (2006), Carrière (2008), Molaei (2014)). While the use of steel strands as tension bracing elements proves to be an effective technique, the resulting stiffening effects on the frames lead to increased seismic force demands and higher based shear, as well as increased axial forces on the attached columns, potentially generating net tension, foundation uplift and excessive compression. Relatively low elongation characteristics of high-strength cables and slack caused by yielding strands and associated pinching of hysteresis curves reduce potential energy dissipation capacity. The current research aims to improve the previously observed deficiencies of the system. One of the improvements involve the use of shape memory alloys (SMA) in the middle of the cables, which reduce/eliminate residual deformations upon yielding and associated pinching of the hysteresis curves. SMA allows energy dissipation in the system while forcing the structure to recover from its inelastic deformations because of the flag-shape hysteretic characteristics of the material. The feasibility of the cable-SMA assembly as tension brace elements is illustrated through dynamic analyses of selected prototype buildings. The other improvement is the development of progressively engaging, initially loose multiple strands as tension cables. These cables are placed loosely to engage in seismic resistance at pre-determined drift levels, thereby eliminating premature increase in seismic force demands until their participation is required as the frame capacity is reached. Tests of a large-scale reinforced concrete frame, designed following the requirements of the 1965 National Building Code of Canada NRC (1965) as representative of existing older frame buildings in Canada, are conducted under simulated seismic loading to assess the effectiveness of the proposed system. The verification of the concept is extended analytically to prototype buildings and the effectiveness of the system is demonstrated for mid-rise and low-rise frame buildings.

Published
2021
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4. Relationship between self-care behaviors and glycosylated hemoglobin level in diabetic patients.

Author

Maleka, Ali, Khosravi, Sadegh, Charkazi, Abdorrahman, Pahlavanzaded, Bagher, Khosravi, Zahra, and Khosravi, Mehdi

Abstract

Background and Objective: Diabetes is one of the most common chronic diseases and also the biggest health problem in all countries. The world health organization has called it a silent epidemic. Self-care is one of the most important factors in controlling blood sugar in diabetics’ patients. This study was done to determine the relationship between self-care and glycosylated hemoglobin level diabetic patients in rural area in Golestan Province, northern Iran. Methods: This descriptive-analytical study was done on 239 male and female patients with type 2 diabetes (56.92±10.70 years) in rural area in Golestan Province, northern Iran during 2016. Data collection tool were a standard diabetes self-care questionnaire with demographic variables and HbA1C test. Completion of data and sampling was done by referring to the health center and calling patients. Results: There was no significant relationship between glycemic controls with any of the self-care items studied. Mean of HbA1c was 8.23±1.85%. 97 patients (40.6%) had good blood sugar control (less than 7.5%). Patient's selfcare had a mean of 3.58, of which the highest score was related to the dietary regimen (6.60) and the lowest was related to self-monitoring of blood glucose (0.88) and regular physical activity (2.3). Conclusion: Self-care of the patients was moderate. Interventions to increase self-care of patients are recommended in this area. [ABSTRACT FROM AUTHOR]

Published
2021

5. Solar Panels: Blind Spots and Risks for Insurers and Owners.

Author

Daee, Ben and Khosravi, Sadegh

Subjects
SOLAR panels, RENEWABLE energy sources, PHOTOVOLTAIC power systems, ENGINEERING standards, SOLAR energy, BUILDING-integrated photovoltaic systems, SOLAR cells
Abstract

Conclusion Installation of solar panels on flat or sloped roofs may alter roof geometry and capacity, especially when factoring in exposure to environmental loads. For residential sloped roofs where PV panels are flush-mounted, the alteration in the original amount of snow Load is not typically critical since the roof geometry remains relatively unchanged although the load distribution on the roof framing may change. If detailed drawings for the Location of arrays are not produced, the actual loads on the roof will differ from the design Loads, as repositioning of solar arrays on the roof in the construction stage is Likely, Water Intrusion and Ponding. [Extracted from the article]

Published
2022

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