Impact of introducing semi-rigid moment frames on seismic response of braced frames

Maximum seismic inelastic drift demand in a steel building with braced frames as primary seismic-force-resisting (SFR) system tends to concentrate in few stories without considering inherent participation of designed gravity-force-resisting (GFR) system in actual structural stiffness and strength. The influence of GFR system on stiffness and strength can be taken into account by considering the composite action in beam-to-column shear connections that exist in modern steel building construction to form actual semi-rigid moment-resisting frames. Therefore, modeling semi-rigid moment frames as an equivalent to the GFR system in braced frame buildings could be utilized as a representative to the strength provided by gravity frames. This paper presents a seismic evaluation of a six-story chevron braced frame, with and without semi-rigid moment frame. Four different cases are investigated under a set of ground motions and results are discussed in terms of story drift distribution along the height. The results pointed out that the current findings lay a foundation to conduct further investigation on the seismic performance of braced frames as designed SFR system together with GFR system.Scopus - Affiliation ID: 6010507

Seismic evaluation of square HSS braces in SCBF using regression analysis

Since the 1990s, structural engineering practice geared toward the use of hollow structural sections (HSS), notably square HSS, for their economy, and ease of design and construction. According to the AISC Seismic Provisions, during a severe earthquake, these braces could undergo post-buckling axial deformations 10 to 20 times their yielding deformation. However, recent experimental studies indicate that braces made of square HSS, depending on their size, width-to-thickness, and slenderness ratio, are vulnerable to fracture even prior to 10. Therefore, relying on past experimental studies comprised of a few square HSS specimens to develop seismic requirements for SCBF with square HSS could lead to underestimation of the seismic risk. This paper aims to evaluate the fracture risk of braces in existing SCBFs designed in accordance with AISC 341-05 and AISC 341-16 through incremental dynamic analyses (IDA) along with experimentally developed regression model that estimates fracture.Scopus - Affiliation ID: 6010507

Contribution of gravity frames to seismic performance of steel moment resisting frames

Traditionally, lateral stiffness and strength of the gravity frames in steel buildings are neglected in structural analysis. During the past earthquakes, such as Northridge, USA, 1994 and Kobe, Japan, 1995, unexpected failures were detected at beam-to-column connections of steel moment resisting frames (MRFs). In the aftermath of these earthquakes, extensive research has been carried out to reveal the causes of these failures. Based on the detailed observations, it is likely that the reserve capacity provided by the gravity frames prevented the highly damaged steel buildings from collapsing, since majority of the moment-resisting connections failed prematurely during the Northridge earthquake (1994). Even though the influence of gravity frames (GFs) on structural behavior can be substantial, little attention is paid to evaluate its impact on structural response. With this paper, the contribution of interior GFs in seismic performance of special moment resisting steel frames (SMRFs) is evaluated. For this purpose, 4- and 9-story SMRFs were designed in accordance with the requirements of Draft Turkish Seismic Code (2016). The frames are, then, subjected to incremental dynamic analysis. To evaluate the contribution of the interior GFs on the overall seismic performance of structural system, inelastic behavior of shear tab (simple) connections at beam-to-gravity-only columns were idealized as semi-rigid joints. A general purpose structural analysis software, ETABS, is utilized for the analyses. The results of the study are presented in terms of story drifts, base shear vs. roof displacement

The comparison of local tumor control after microwave ablation, surgical resection and combined treatment for colorectal liver metastases

Aim. We aimed to compare the local therapeutic efficiency of microwave ablation (MWA), surgical resection, and combined treatment, assess the outcomes, and identify predictive factors for local treatment response in colorectal liver metastases (CLMs). Methods. From March 2013 to September 2019, a total of 54 patients with 302 CLMs were enrolled in this retrospective study. Eleven patients (20.4%) were treated with MWA, 9 patients (16.7%) with surgery, and 34 patients (63%) with the combined method. Univariate and multivariate analyses were performed to investigate overall survival (OS) and hepatic progression-free survival (HPFS) using the Cox proportional hazard regression model. The logistic regression analysis was used to identify the predictive factors for the local treatment response. Results. Total treatment response was achieved in 46.3% (n=25) of the patients. Local tumor progression was seen in 7.4% (n=4) of the patients, and the rate of intrahepatic distal recurrence was 46.3% (n=25). There were no significant differences in HPFS and OS between the three groups (p=0.56 and 0.90, respectively). Younger age

Propuesta de guía de implementación de un sistema de gestión de seguridad y salud en el trabajo basado en la norma INTE/ISO 45001:2018 para la empresa Corporación de Profesionales en Ingeniería S.A.

Proyecto de Graduación (Licenciatura en Ingeniería en Seguridad Laboral e Higiene Ambiental) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería en Seguridad Laboral e Higiene Ambiental, 2019.The project was carried out in the company Corporación de Profesionales en Ingeniería S.A., dedicated to the construction sector. The objective was to develop a guide for the implementation of a Work Health and Safety Management System based on the INTE/ISO 45001: 2018 standard. For the development of the proposal, the current management of the company was initially analyzed through a review of documents, the application of the checklist based on NTP 308, a survey for managers and another for collaborators. Subsequently, the analysis of the organization's context, internal and external, is carried out through an analysis of PESTEL and finally the information is synthesized in a SWOT. Then an assessment of risks and opportunities is carried out by means of a non-participatory observation and the guidelines for the verification of conditions in the construction sector are applied in the projects to be subsequently evaluated through the risk evaluation matrix according to the standard INTE 31-06-07: 2011. After analyzing the tools, results were obtained such as the absence of a formal written commitment from management, the lack of documentation and the presence of important risks for workers in the activities they carry out. This is summarized in the current management of the company in health and safety has great opportunities for improvement and shows the need for immediate intervention measures to improve the situation, which leads to the implementation guide of a health and safety system in work to improve the working conditions of the organization.El proyecto se realizó en la empresa Corporación de Profesionales en Ingeniería S.A., dedicada al sector construcción. El objetivo fue desarrollar una guía de implementación de un Sistema de Gestión de Salud y Seguridad en el trabajo basada en la norma INTE/ISO 45001:2018. Para el desarrollo de la propuesta se analizó inicialmente la gestión actual de la empresa por medio de una revisión de documentos, la aplicación de la lista de verificación basada en la NTP 308, una encuesta para los gerentes y otra a los colaboradores. Posteriormente se realiza el análisis del contexto de la organización, interno y externo por medio de un análisis de PESTEL y por último se sintetiza la información en un FODA. Luego se realiza una evaluación de riesgos y oportunidades por medio de una observación no participativa y se aplica en los proyectos la guía de verificación de condiciones en el sector construcción para posteriormente ser valorados mediante la matriz de evaluación de riesgos según la norma INTE 31-06-07:2011. Tras el análisis de las herramientas se obtuvieron resultados como la ausencia de un compromiso formal por escrito de parte de la dirección, la inexistencia de documentación y la presencia de riesgos importantes para los trabajadores en las actividades que desarrollan. Esto se sintetiza en que la gestión actual de la empresa en salud y seguridad tiene grandes oportunidades de mejora y muestra la necesidad de medidas de intervención inmediatas para mejorar la situación, lo que conlleva a la guía de implementación de un sistema de salud y seguridad en el trabajo para mejorar las condiciones laborales de la organización

Effect of granulated furnace slag on properties self-compacting concretes

06.03.2018 tarih ve 30352 sayılı Resmi gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Beton üretiminde genellikle doğal agregalar tercih edilmesi, doğal hammadde kaynaklarında azalmaya yol açmakta ve çevreye olumsuz etki bırakmaktadır. Beton hacminin yaklaşık %70-80'i agregalardan oluşmaktadır. Bu nedenle hammaddelerin korunumu için alternatif kaynaklara yönlenilmesi gereklidir. Granüle yüksek fırın cürufu yapısı nedeniyle çimento ve beton sektöründe sıklıkla kullanılan bir malzemedir. Bu kullanım, çimento yerine olduğu gibi bazen agrega yerine de kullanılabilmektedir. Literatürde yüksek fırın cürufu agregalarının beton agregalarının tamamı veya bir kısmı yerine ve sıcak asfalt yüzey uygulamalarında kullanımına dair çeşitli çalımalar mevcuttur. Bu Şekilde doğal kaynakların korunumu sağlanmakta, aynı zamanda bir yan ürün olan ve değerlendirilmediğinde çevresel sorunlara yol açabilen yüksek fırın cürufu değerlendirilmektedir. Bu çalışmada, 400 kg/m3 çimento, 100 kg/m3 uçucu kül ve 0,45 sabit s/ç içeriği sahip kendiliğinden yerleşen betonlarda granüle yüksek fırın cürufu agregası, ince agrega yerine %0, 25, 50 ve 75 oranlarında kullanılmıştır. Üretilen betonların taze hal ile 7, 28 ve 90 günlük sertleşmiş özellikleri incelenmiştir. Taze hal özellikleri olarak taze birim hacim ağırlıkları, çökme-yayılma değerleri ile T500 süreleri, J halkası ile T500 süreleri, V hunisi, reoloji değerleri ölçülmüştür. Sertleşmiş hal özellikleri ise sertleşmiş birim hacim ağırlık ölçümü, basınç dayanımı testi, Schmidt çekici testi, ultrases hızı ölçümü, kılcallık ve elastisite deneyi yapılarak değerlendirilmiştir. Elde edilen sonuçlara göre %25 ve 50 oranlarında taze hal özelliklerin iyileştiği, ancak basınç dayanımlarının granüle yüksek fırın cürufu agregası miktarı arttıkça azaldığı görülmüştür.Reserves of natural raw materials decrease and negative effect on environment occurs since natural aggregates have been usually preferred. Concrete contains about 70-80% aggregates in volume. So, to protect natural raw materials alternative ways are needed. Granulated furnace slag is a by-product that has been widely used in concrete and cement sectors. It can be used both for cement as replacement and for aggregate in concrete. In literature, studies exist about the usage of granulated furnace slag as aggregates in concrete as partially replacement and asphalt surface application. By this way, granulated furnace slag causing environmentally problem finds a usage area to eliminate its negative effect. In this study, granulated furnace slag was used as fine aggregate in the ratios of 0%, 25%, 50% and 75% to produce concrete with 400 kg/m3 cement, 100 kg/m3 fly ash and 0.45 w/c ratio. Fresh concrete properties and hardened concrete properties at 7, 28 and 90 days were studied. Unit weight of fresh concrete, slump-flow, T500 time, J ring, V funnel and rheological properties were measured. On hardened concrete, unit weight, compressive strength, Schmidt hardness, ultrasound, capillarity and elasticity modulus were determined. According to results obtained, when it is used at the ratio of 25% and 50% workability of fresh concrete increases while compressive strength decreases

Yaklaşık sıfır enerjili binalarda kullanılan havadan havaya plakalı ısı geri kazanım cihazlarının enerji performansına katkısının incelenmesi ve test prosedürleri

Günümüzde fosil enerji kaynakları hızla tükenmektedir. Bu kaynakların sebep olduğu emisyonlar nedeniyle küresel ısınma ve çevre kirliliği insanları etkileyen en büyük problemlerdendir. Yapılan araştırmalara göre çevre kirliliğinin ve sera gazlarının emisyonunun %33ünden fazlasını inşaat sektörü oluşturmaktadır. Bu konuyla ilgili standartlar ve kanunlar oluşturularak çevre dostu çözümler getirilmiştir. Yaklaşık sıfır enerjili bina sistemleri de bu standartlar ve kanunlar çerçevesinde geliştirilmiştir. Yaklaşık sıfır enerjili binalar tasarlanırken enerji verimliliğinden iç hava kalitesine kadar birçok kriter dikkate alınmaktadır. Binalarda günümüzdeki enerji ihtiyacı ve iç hava kalitesi göz önünde bulundurulduğunda ısı geri kazanımlı havalandırma cihazları büyük bir önem taşımaktadır. Havalandırma sistemlerinde uygulanan ısı geri kazanımlı havalandırma cihazları hem işletme masraflarını düşürerek enerji tasarrufu sağlarken hem de içeriye sağladığı taze hava ile iç ortam kalitesini arttırmaktadır. Bu tez çalışmasının amacı, yaklaşık sıfır enerjili bina sistemleri için çıkartılan ve farklı ülkelerde uygulanan kanun-yönetmeliklerin incelenmesi ve kullanılan sertifikasyon sistemlerinin karşılaştırılmasıdır. Buna ek olarak, yaklaşık sıfır enerjili binalarda kullanılması zorunlu olan ısı geri kazanımlı havalandırma cihazları ve bu cihazların sahip olduğu komponentler ile bu cihazlar için geliştirilen standartlar ve test yöntemleri anlatılmıştır. Ayrıca bir ısı geri kazanım cihazının standartlara göre testleri gerçekleştirilmiş ve bu cihazın bir binada kullanımının enerji verimliliğine katkısı incelenmiştir.Today, fossil-based energy sources are rapidly consuming. Global warming and environmental pollution are the biggest problems affecting people because of the emissions caused by these sources. According to the researches carried out, the environmental pollution and the fact that more than 33% of greenhouse gas emissions originate from the construction sector. Environment-friendly solutions have been developed by establishing relevant standards and laws about this issue. Nearly zero energy building systems have also been developed within these standards and laws. There are many criteria from energy efficiency to indoor air quality when designing nearly zero energy buildings. Considering today's energy needs and indoor air quality in buildings, heat recovery ventilation units are very important. The heat recovery ventilation units applied in the ventilation systems both reduce energy costs by lowering the operating expenses and increase the quality of indoor environment with the fresh air provided. The aim of this study is compare certification systems used for nearly zero energy buildings and examination of regulations for different countries.In addition to this aim, different standards and test methods developed for heat recovery units and their components are explained which are required to use in nearly zero buildings. Furthermore, tests have been carried out according to the standards for a heat recovery unit and the contribution to building energy efficiency of this heat recovery unit has been examine

Seismic assessment of ductile concentrically braced frames with HSS bracings

A study on the seismic ductility demands on square HSS braces in special concentrically braced frames (SCBFs) is presented to address the seismic risk of braces in existing SCBF buildings designed according to both previous and current AISC Seismic Provisions. First, the paper discusses the development of ductility-based fragility curves by employing specimens with various width-to-thickness and slenderness ratios collected from 16 experimental programs from 1978 to today. Second, the constructed fragility curves are used to estimate the vulnerability of square HSS braces to the damage state of fracture using the brace ductility demand as engineering demand parameter. Then, the seismic risk of braces in terms of fatigue life is evaluated under 30 earthquake ground motions using a seven-story office building designed following requirements of previous and current design practice. The study concludes that braces in SCBF designed in compliance with the previous and current AISC Seismic Provisions are subject to a high probability of fracture under earthquake ground motions characterized by different intensity levels, which in turn might lead to underestimation of the overall seismic risk.WOS:000471083200028Scopus - Affiliation ID: 60105072Science Citation Index ExpandedQ1ArticleUluslararası işbirliği ile yapılan - EVETTemmuz2019YÖK - 2018-1

How to select which anterior sector drainage veins to reconstruct in right lobe living donor liver transplantation?

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