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This study presents an experimental investigation into the seismic retrofit of tubular steel braces using carbon fiber reinforced polymer (CFRP) members. CFRP retrofitting of net sections for compact tubes are proposed for delaying potential local net section failure. A total of almost full-scale three (TB-1, TB-2, and TB-3) compact steel tubular specimens were designed per AISC specifications, constructed, and cyclically tested to fracture. Retrofitted braces, when compared to the reference specimen, developed fuller hysteretic curves. Increase in cumulative hysteretic energy dissipation and the elongation in fracture life in the specimen retrofitted with CFRP plates and CFRP sheet wraps at net sections are observed during testing. This resulted in a maximum of 82.5% more dissipated energy for compact tube specimens. Also, this retrofit provided a longer experimental fracture life (maximum 59% more). Due to fracture initiation during the last cycles, significant reductions in strength and stiffness have been obtained. No significant change (maximum 10%) in the brace stiffness was observed, which could be desirable in seismic retrofit applications. Pushover analysis per FEMA 356 for the bare specimen shows that FEMA does not represent actual brace behavior in the compression side although pushover and experimental results are in good agreement in the tension side., Çelik tüp çaprazların deprem etkilerine karşı karbon lifli polimer (CFRP) elemanlarla güçlendirilmesi deneysel olarak incelenmiştir. Zayıflatılmış uç kesitten olası kopmanın geciktirilmesi için bu bölgelerin CFRP elemanlarla (plaka ve kumaş) güçlendirilmesi önerilmiştir. Zayıflatılmış kesitte güçlendirmenin etkinliğini incelemek için üç adet kompakt kesitli, gerçeğe yakın ölçekli numune AISC yönetmeliklerine uygun olarak tasarlanmış ve kopmaya ulaşıncaya kadar yön değiştiren tekrarlı yükler altında denenmişlerdir. Referans numuneyle karşılaştırıldıklarında, beklendiği üzere, güçlendirilmiş numunelerin daha dolu histeretik eğrilere sahip olduğu görülmüştür. Zayıflatılmış uç bölgenin yan yüzlerine önce CFRP plaka sonrasında da kumaş ile sarılmasıyla numunenin kümülatif enerji tüketiminde artış ve kopma ömründe uzama görülmüştür. Güçlendirme, kopma anında en çok %82.5 oranında daha fazla enerjinin tüketilmesine katkıda bulunmuş, kopma ömürlerinde ise en çok %59 oranında artış görülmüştür. Süneklikteki artışa karşın son çevrimlerde kopma başlangıcı nedeniyle dayanım ve rijitlikte önemli denilebilecek azalmalar elde edilmiştir. Çapraz rijitliklerindeki değişim en fazla %10 civarında olduğundan önerilen yöntem çaprazlı çelik sistemlerin deprem etkilerine karşı güçlendirme uygulamaları için uygundur. FEMA 356’ya göre tanımlanan eksenel plastik mafsallı çaprazlara yapılan itme (pushover) analizi sonucunda FEMA’nın basınç bölgesinde gerçek davranışı yansıtmadığı, çekme bölgesinde ise uyumlu sonuçlar elde edildiği görülmüştür.

Bir tür metalik sönümleyiciler olarak kabul edilen Burkulması önlenmiş Çaprazlar (BÖÇ) önemli depremlerde çekme ve basınçta akarak dengeli bir histeretik davranış gösterirler. Bu çalışmada farklı çelik uç detayı malzemesine sahip BÖÇ’lerin yön değiştiren tekrarlı yükler altındaki histeretik davranışına ilişkin deneysel bulgu ve değerlendirmeleri verilmektir. Denenen BÖÇ’ler için kuvvet-yerdeğiştirme histeretik eğrileri, histeretik enerji yutma miktarları ve etkili sönüm oranları hesaplanarak karşılaştırmalar yapılmıştır. Özgün detaylar ile üretilen ve denenen BÖÇ’lerin yeterli bir performans gösterdiği ve bu performansının ileride yapılabilecek çalışmalarla iyileştirilebileceği sonucuna varılmıştır.

This article presents the analysis of the structure, energy and cost efficiency of three lightweight structural systems – wood light frames (WLF), lightweight steel frames (LGSF) and 3D sandwich (3DSP) panels – during their useful life. The structural systems focussed upon in this study are commonly used in Eastern Europe with specific reference to Turkey. The structural analysis and design was carried out using ETABS while EnergyPlus was used in the analysis of the energy consumption of the buildings. The results of the structural analysis of the three alternative construction systems show that 3DSP has better structural behaviour in terms of resistance against lateral loads. The thermal performance evaluation of the walls and ceilings shows that the WLF and LGSF walls have better insulation values (12.5% lower U-value) while the roof construction of the 3DSP has much better insulation performance (70% lower U-value). Moreover, the building designed with 3DSP requires 11% less energy for total heating and cooling during one year. The information for the building industry in Turkey shows that the cost of construction for 3DSP construction is 34.6% lower than for WLF and 27.7% lower than LGSF.

This paper examines the shape collapse problem that occurs when registering a pair of images or a population of images of the brain to a reference (target) image coordinate system using diffeomorphic image registration. Shape collapse occurs when a foreground or background structure in an image with non-zero volume is transformed into a set of zero or near zero volume as measured on a discrete voxel lattice in the target image coordinate system. Shape collapse may occur during image registration when the moving image has a structure that is either missing or does not sufficiently overlap the corresponding structure in the target image[4]. Such a problem is common in image registration algorithms with large degrees of freedom such as many diffeomorphic image registration algorithms. Shape collapse is a concern when mapping functional data. For example, loss of signal may occur when mapping functional data such as fMRI, PET, SPECT using a transformation with a shape collapse if the functional signal occurs at the collapse region. This paper proposes an novel shape collapse measurement algorithm to detect the regions of shape collapse after image registration in pairwise registration. We further compute the shape collapse for a population of pairwise transformations such as occurs when registering many images to a common atlas coordinate system. Experiments are presented using the SyN diffeomorphic image registration algorithm. We demonstrate how changing the input parameters to the SyN registration algorithm can mitigate some of the collapse image registration artifacts.

Registering lung CT images is an important problem for many applications including tracking lung motion over the breathing cycle, tracking anatomical and function changes over time, and detecting abnormal mechanical properties of the lung. This paper compares and contrasts current-and varifold-based diffeomorphic image registration approaches for registering tree-like structures of the lung. In these approaches, curve-like structures in the lung—for example, the skeletons of vessels and airways segmentation—are represented by currents or varifolds in the dual space of a Reproducing Kernel Hilbert Space (RKHS). Current and varifold representations are discretized and are parameterized via of a collection of momenta. A momenta corresponds to a line segment via the coordinates of the center of the line segment and the tangent direction of the line segment at the center. A varifold-based registration approach is similar to currents except that two varifold representations are aligned independent of the tangent vector orientation. An advantage of varifolds over currents is that the orientation of the tangent vectors can be difficult to determine especially when the vessel and airway trees are not connected. In this paper, we examine the image registration sensitivity and accuracy of current-and varifold-based registration as a function of the number and location of momentum used to represent tree like-structures in the lung. The registrations presented in this paper were generated using the Deformetrica software package ([Durrleman et al. 2014]).

In this paper, we discuss the relationship between conformal transformations of [Formula: see text] and the curvature of curves. First, for any non-circular closed curve, there exists a length-preserving inversion such that the maximum pointwise absolute curvature can be made arbitrarily large. In contrast, we show that the total absolute curvatures of a family of curves conformally equivalent to a given simple or simple closed curve are uniformly bounded. Furthermore, we show that the total absolute curvature of an inverted regular [Formula: see text] simple closed curve as a function of inversion center and radius is removably discontinuous along the curve with exactly a [Formula: see text] drop, and continuous elsewhere.

The thickness, NIR (K) of a knot or link K is defined to be the radius of the largest open solid tube one can put around the curve without any self intersections of the normal discs, which is also known as the normal injectivity radius of K. For C1,1 curves K, [Formula: see text], where κ(K) is the generalized curvature, and the double critical self distance DCSD (K) is the shortest length of the segments perpendicular to K at both end points. The knots and links in ideal shapes (or tight knots or links) belong to the minima of ropelength = length/thickness within a fixed isotopy class. In this article, we prove that NIR (K) = ½ DCSC (K), for every relative minimum K of ropelength in Rn for certain dimensions n, including n = 3.

Strength and stiffness of panel and joint in non-diaphragm CHS-column to H-beam connection were experimentally investigated Herein, the panel means the cylindrical stub circumscribed by outer planes of the beam and the column, and the joint means the butt seam between the column wall and the beam end. Two types of specimen were tested: one is an X-shaped frame whose panel is subjected to shear, and the other is a 3-point bending specimen whose panel is free from shear. In result, the joint strength and stiffness are well predicted by the previously proposed formulae irrespective of the existence of shear in the panel, and the panel strength and stiffness are also well predicted by the well known formulae given for diaphragm connections. This suggests that the interaction between panel and joint of the non-diaphragm connection can be ignored in structural design. Japan Society for the Promotion of Science, JSPS: 15J10631

This paper experimentally investigates the cyclic inelastic performance of concentrically braced frames with and without cold formed steel stud (CFSS) infills designed to laterally restrain braces and delay their buckling. Specimens have either diagonal tube or solid bar braces with and without CFSS and U brackets providing out-of-plane and in-plane buckling restraint. Behavioral characteristics of the specimens are quantified with an emphasis on hysteretic energy dissipation. Experimental results show that, at the same ductility levels, the cumulative energy dissipation of braced frames can be significantly increased when CFSS members are used to laterally restrain the braces against buckling. However, when tubular cross sections are used for braces, local buckling led to a reduced fracture life compared to the case without CFSS members. CFSS members appear to be relatively more effective when solid bar braces having large slenderness (tension-only braces) are used, since the difference between dissipated energies obtained with and without studs is substantial.

The potential benefit of vitamin K as a therapeutic in osteoporosis is controversial and the vitamin K regimen being used clinically (45 mg/day) employs doses that are many times higher than required to ensure maximal gamma‐carboxylation of the vitamin K‐dependent bone proteins. We therefore tested the hypothesis that vitamin K catabolites, 5‐carbon (CAN5C) and 7‐carbon carboxylic acid (CAN7C) aliphatic side‐chain derivatives of the naphthoquinone moiety exert an osteotrophic role consistent with the treatment of osteoporosis.

Some properties of fundamental groups of Riemannian manifolds M will be studied without a lower bound assumption on Ricci curvature. The main method is to relate the local packing to global packing instead of using the Bishop-Gromov relative volume comparison. This method allows us to control the volume growth of the universal cover M and yields bounds on the number of generators of π 1 (M) in terms of some isoembolic geometric invariants of M.

Intense research is being done in the field of Buckling Restrained Brace (BRB) technology to seek more cost effective and reliable solutions. To investigate performance under cyclic loading, two full scale steel-core BRB specimens (labeled as TURKBRACE BRB-SCI and TURKBRACE BRB-SCII) with simple end details (as an alternative to existing details in commercially available BRBs) have been designed to AISC specification, manufactured, and cyclically tested in the Structural and Earthquake Engineering Laboratory (STEEL) of the Technical University of Istanbul. These specimens use single, large diameter bolted (pinned) end connections and rectangular shaped steel core plates as the core materials of S235JR and S355JR for BRB-SCI and BRB-SCII, respectively. Rectangular core plate expands at the ends to form a cruciform section as the elastic (non-dissipative) parts of the brace. The core is surrounded by a thin steel tube infilled with a high strength (64MPa) grout material as the buckling restraining system. A teflon based unbonded surface system was used on the core member’s surface. Material coupon tests from the core and standard compression tests of the infill mortar were performed. A diagonal configuration for the braces in an L-shaped testing setup (a vertical steel I-shaped column hinged on the I-shaped steel foundation beam that was attached to the strong floor) was used. The system was loaded horizontally that developed axial tension and compression deformations in the diagonal brace. Experimental results show that maximum drifts of 3.17% and 3.55% for BRB-SCI and-SCII, respectively. Note that no fractures in the welds or any signs of local or global instability were observed during testing. Experimental hysteretic curves, behavioral values such as maximum strength in tension and compression cycles, variation of brace stiffness with displacement cycles, hysteretic damping (ξmax= 40%), and cumulative hysteretic energy dissipation values are given. These observations reveal that BRB-SCI performed slightly better than BRB-SCII since this BRB used a longer core length, resulting in larger dissipated energy. A maximum displacement ductility of μ=10 was obtained for both BRB-SCI and BRB-SCII, respectively. Both BRBs achieved the desired behavior while no global buckling occurred under inelastic displacement cycles. Stable, repetitive, and fuller hysteretic curves were obtained. As a result, the proposed steel core BRBs having unique end details showed promise for use in new buildings/bridges or as a retrofitting technique in buildings/bridges that lack strength, stiffness, and ductility.

Composite reinforcing bars (rebars) that are used in concrete members with high performance (strength and durability) properties could have beneficial effects on the behavior of these members. This is especially vital when a building is constructed in an aggressive environment, for instance a corrosive environment. Although tension capacity/weight (or volume) ratios in composite rebars (carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), etc.) are very high when compared to steel rebars, major weaknesses in concrete members reinforced with these composite rebars may be the potential consequences of relatively poor bonding capacity. This may even be more crucial when the member is subjected to cyclic loading. Although monotonic bond tests are available in the literature, only limited experimental studies exist on bond characteristics under cyclic loading conditions. In order to fill this gap and propose preliminary design recommendations, 10 specimens of 10-mm-diameter ribbed CFRP rebars embedded in specially designed high strength concrete (f’c = 70 MPa) blocks were subjected to monotonic and cyclic pullout tests. The experimental results showed that cyclically loaded CFRP rebars had less bond strength than those companion specimens loaded monotonically.

Tubular steel braces with carbon fiber reinforced polymer (CFRP) reinforced net sections are proposed and experimentally investigated. Quasi-static reversed cyclic testing protocol is applied to compare the inelastic performances of these braces with and without net section reinforcement. Special emphasis is placed on hysteretic energy dissipation. Three near fullscale specimens were designed and tested to fracture. Experimental results show that the use of CFRP members (both laminates and sheets) to improve the hysteretic behavior of tubular braces is promising as a retrofit technique in steel framed buildings lacking ductile brace to gusset connections. Repaired braces, when compared to the reference brace, reached larger story shear strength (or larger axial tension and compression capacities) up to 15%. This resulted in larger (4.3% more) cumulative dissipated energy at a prescribed drift ratio, and 82.5% more at fracture. Note that no significant change (max. 10%) in the brace stiffness was observed, which could be desirable in seismic retrofit applications.

Wood and/or iron tension members in the form of either tie bars (both wood and iron) in historic masonry arches or externally applied tension rings (iron) of masonry domes have been used in historic buildings especially in the areas that are vulnerable to severe earthquake excitations. Earthquake reconnaissance investigations revealed that masonry arches and domes with tension members showed satisfactory behavior under earthquake loading. To investigate their effectiveness on behavior, three case studies are analyzed from Turkey. The first one is a 16 th century mosque having major structural cracks on its 25m-diameter brick masonry dome. Combined steel and CFRP sheets as tension members at several dome levels are proposed as a seismic retrofit measure. Significant improvement is obtained in response, leading to maximum 60% reduction in stresses. The second case study is a stone masonry vault having damaged wooden tie bars. Similarly, numerical results show that stresses as well as deformations can be reduced up to 50% by replacing the old ties with the new wooden tie bars. The third one is a 508year-old tomb having a nearly collapsed brick masonry dome. At the support level of the dome, externally applied steel rings were used as tension members to limit stresses and deformations. Similar amounts of reductions in stresses are obtained. This study also shows that both traditional and contemporary retrofit strategies can be used in the same project when required.