Performance of masonry buildings during the 20 and 27 December 2007 Bala (Ankara) earthquakes in Turkey

This paper evaluates the performance of masonry buildings during the 20 and 27 December 2007 Bala (Ankara) earthquakes. Bala is a township located 50 km southeast from Ankara city in Turkey. The majority of the buildings in the affected region are built in masonry. Most of masonry buildings were formed with random or coursed stone and mud brick walls without any reinforcement. Many of these buildings were damaged or had collapsed. The cracking and failure patterns of the buildings are examined and interpreted according to current provisions for earthquake resistance of masonry structures. The damages are due to several reasons such as poor construction quality and poor workmanship of the buildings. In addition to these reasons, the two earthquakes hit the buildings within seven days, causing progressive damage

Stochastic Seismic Analysis of a Cable-Stayed Bridge Using CFRP Cables

Fiber reinforced polymer (FRP) composites have found increasingly wide applications in civil engineering due to their high strength-to-weight ratio and high corrosion resistance for last two decades. This paper presents a numerical study on the stochastic seismic analysis of a cablestayed bridge subjected to earthquake ground motion using carbon fiber reinforced polymer (CFRP) cables. Jindo Bridge is chosen and schemed using CFRP cables. The cross-sectional areas of CFRP cables are determined by the principle of either equivalent cable stiffness or equivalent cable strength. The analysis of the selected bridge is conducted and the results obtained for CFRP cables are compared with steel counterpart. The results indicate that response values obtained for CFRP cables correspond well with those of the steel cables

Asma Köprülerin Analiz Yöntemleri

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Bu çalışmada, asma köprülerin deterministik ve stokastik dinamik analizleri; geometrik olarak lineer olmayan davranış dikkate alınarak incelenmektedir. Uygulama olarak Boğaziçi Asma Köprüsü seçilmiştir. Yer hareketi olarak 1971 San Fernando depremi Pacoima Barajı S16E bileşeni ile 1992 Erzincan depremi doğu-batı bileşeni ivme kayıtları kullanılmaktadır. Stokastik analizlerde yer hareketini temsil etmek üzere Clough ve Penzien tarafından düzeltilerek elde edilen filtre edilmiş beyaz gürültü modeli dikkate alınmaktadır. Yer hareketi modeli, mesnetlere etkiyen yer hareketlerinin yansıma ve kırılmalarla değişebilir olmasından kaynaklanan korelasyon etkisini, dalga yayılma etkisini ve zemin özelliklerinin yer hareketine etkisini içermektedir. Analizler sonucunda köprü kuleleri ve tabliyesine ait yerdeğiştirme ve kesit tesirleri elde edilmiştir. Yer tabakasının karmaşık yapısından dolayı, yer hareketlerinin farklı noktalardaki değişiminden doğan etkilerin asma köprüler gibi uzun açıklıklı sistemlerin deterministik ve stokastik analizlerinde dikkate alınması gerektiği vurgulanmaktadır.In this study, deterministic and stochastic dynamic responses of suspension bridges are investigated by considering geometrically nonlinear behavior. Bosporus Suspension Bridge is chosen as an example. S16E component of Pacoima Dam record of 1971 San Fernando earthquake and east-west component of 1992 Erzincan earthquake are used as ground motions. Filtered white noise model modified by Clough and Penzien is considered as a ground motion in the stochastic analyses. The ground motion model includes the effects of incoherence, wave passage, and site response. The bridge towers and deck displacement and internal forces are obtained in the end of the analyses. Because of the complex nature of earth crust, it is emphasized that the multiple support seismic excitations should be taken into account in the deterministic and stochastic analyses of long span structures like suspension bridges

Dynamic Analysis of a Suspension Bridge Using CFRP Composite Material

Fiber reinforced polymer (FRP) is a class of advanced composite materials used in civil engineering because of their advantages when these materials are compared to traditional ones. These advantages are light weight, high stiffness-to-weight and strength-to-weight ratios, damping capabilities, and high resistance to environmental degradation. This paper presents a numerical study on the dynamic analysis of a suspension bridge subjected to earthquake ground motion using carbon fiber reinforced polymer (CFRP) materials. Bosporus Suspension Bridge is selected for application. The cross-sectional areas of CFRP elements are determined by the principle of either equivalent-stiffness or equivalent-strength methods. The YPT330 component of Yarımca station records of 1999 Kocaeli Earthquake is chosen as a ground motion. The calculated displacement and internal forces occurring in the towers and deck are examined. It is seen from the analyses results that, CFRP material are more effective than steel material for suspension bridges

Improvements in Fabrication of Sand/Binder Cores for Casting

Three improvements have been devised for the cold-box process, which is a special molding process used to make sand/binder cores for casting hollow metal parts. These improvements are: The use of fiber-reinforced composite binder materials (in contradistinction to the non-fiber-reinforced binders used heretofore), The substitution of a directed-vortex core-blowing subprocess for a prior core-blowing process that involved a movable gassing plate, and The use of filters made from filtration-grade fabrics to prevent clogging of vents. For reasons that exceed the scope of this article, most foundries have adopted the cold-box process for making cores for casting metals. However, this process is not widely known outside the metal-casting industry; therefore, a description of pertinent aspects of the cold-box process is prerequisite to a meaningful description of the aforementioned improvements. In the cold-box process as practiced heretofore, sand is first mixed with a phenolic resin (considered to be part 1 of a three-part binder) and an isocyanate resin (part 2 of the binder). Then by use of compressed air, the mixture is blown into a core box, which is a mold for forming the core. Next, an amine gas (part 3 of the binder) that acts as a catalyst for polymerization of parts 1 and 2 is blown through the core box. Alternatively, a liquid amine that vaporizes during polymerization can be incorporated into the sand/resin mixture. Once polymerization is complete, the amine gas is purged from the core box by use of compressed air. The finished core is then removed from the core box

A Novel Through-Silicon-Via (TSV) Fabrication Method

The Through Silicon Via (TSV) is expected to be the future of 3-D chip stacking technology for electronic devices. The structure of the TSV interconnect is developed by first etching deep vias into the surface of a wafer, and later filling those vias with a desired metal. Currently, copper based TSVs are the most cost effective mass producible TSVs. Vias filled with copper provide the interconnect ―through‖ the wafer, once both the top and the bottom of the vias are exposed. This provides a solid robust interconnect isolated and protected by the wafer. It also provides the interconnect using much less volume, while reducing the need for a majority of the packaging associated with modern microelectronic packages. Copper based TSVs were produced in this work using two methods, the ADE method and the blind-via method. The ADE method introduces a unique process that is potentially compatible with post-microelectronic manufacturing. The fabricated TSVs from both methods were cross-sectioned for analysis, which revealed successful formation of solid copper TSVs

Experimental Methods for the Analysis of Frost Nucleation and Frost Growth on Hydrophilic and Hydrophobic Coated Flat Plate Surfaces in Forced Convection Channel Flows

An experimental system was designed and built to explore the effect of coated surfaces on frost formation. The experimental system consists of a wind tunnel test apparatus, dew point sensors, thermocouples for temperature measurements, pressure sensors and other devices. The experimental system is equipped with a computerized data acquisition and storage system. The temperature and humidity of the experimental system is computer controlled. The system is suitable to study the condensation and frosting effects on various coated and uncoated surfaces. The formation of frost and ice decreases the energy efficiency of refrigeration systems and of air-source heat pump systems. This work presents experimental data of frost nucleation and frost growth on cold flat plates operating in frosting conditions with air forced convective flow. The plates surfaces had different wettability: from an uncoated aluminum surface with fine finish roughness and contact angle of 75°, to hydrophobic (θ ≈ 110-116°) and hydrophilic (θ ≈ 19-29°) coatings. An experimental technique was developed in order to mimic actual field type operating conditions of convective channel flow experienced by fin structures of heat exchangers of typical air-source heat pump systems. The surface wettability characteristics affected the elapsed time and the initial thickness of the frost before the droplets froze on the test plates. They also affected the starting point for the phase changeover from crystal growth to frost growth. The hydrophobic surface had early phase changeovers and high thresholds of the frost thickness before switching to the frost growth phase due to the presence of large droplets on the surfaces before they froze into ice beads. Fine-finished aluminum surface and hydrophilic coating had delayed phase changeovers and low frost thicknesses with respect to the other surfaces. During pull-down tests, nucleation on the hydrophilic surface occurred quickly, leaving less time for disc-like shaped water droplets to continue to grow in the radial and vertical directions before freezing. Frost thicknesses followed “S” shaped like profiles due to transitions of droplets to ice beads, to crystals growth, and to initial frost accretion on the top of the ice beads. The wettability characteristics of the surfaces affected the elapsed time at which these changeovers occurred and the thresholds of the frost thickness when switching to the frost growth phase

Designing surgical clothing and drapes according to the new technical standards

Hospitals will continue to be the largest consumers of disposables, because of the diverse range of procedures they provide. Favourable growth is forecast for nonwovens. Increasing concern over contamination and nosocomial infections will boost the demand for consumables and disposables surgical gowns and drapes. But, until now neither the manufacturers nor the end users of surgical gowns and drapes could agree on standards. So, a mandatory European standard is being developed to establish basic requirements and test methods for disposable and reusable materials used for surgical gowns and drapes. Once this standard has been adopted, the continued use of cotton textiles and conventional cotton-polyester mixed textiles will become questionable.(undefined

Approaches of Micro-Scale Furniture and Timber Producing Businesses towards Their Waste and Environment.

This study aims to demonstrate the environmental awareness and practices of micro-scale businesses operating in the furniture and timber industry, which are two sub-sectors of the forest products industry. Small and medium-sized businesses have a significant place in every country's economy for their size, production and employment. While 99.9% of the timber, furniture and paper sub-sectors constituting the forest industry are in the small and medium-sized class, 96% of them are in the micro-scale business class. Although the environmental impacts of each of these businesses are limited, they have an important influence in total. Since the late 1980s, environmental impacts of businesses have been an increasing matter of concern. As a result, there is an increasing pressure on small and medium-sized business owners and managers to improve their environmental management practices and performances. A questionnaire was applied to 120 businesses representing 885 micro-scale timber and furniture producing businesses operating in Trabzon by face to face interview in 2015. The clear majority of these businesses believe there is environmental pollution, but the number of businesses that believe their businesses less pollute the environment. In addition, some of the results of the survey are that 66% of the businesses believe that waste cannot be reduced and there is no organization collecting the waste

Comparison of practices related to occupational health and safety in microscale wood product enterprises

Risk factors in the workplace vary according to the sector and scale of the business. Small and mediumsized enterprises, especially those within the scope of the wood-products manufacturing industry, are considered to be risky, and have a relatively high accident rate. Here, we focus on the timber and furniture industries, two subsectors of the wood-products industry. A total of 47 enterprises was visited and asked to participate in a formal structured questionnaire. The findings show that the usage of personal protective equipment (PPE) was low, that lighting was often inadequate, and that these enterprises typically lacked routine organising and cleaning practices. The subsectors and the occupational health and safety practices were found to be independent, and a statistically significant relationship could only be established between the subsectors in terms of the use of dust masks and goggles. Despite the unfavourable working conditions, only one business out of 47 reported having an employee with symptoms of occupational diseases