114,610 research outputs found
V. Subramaniam, Transplanted Indo-British Administration
No full textÉtienne Gilbert. V. Subramaniam, Transplanted Indo-British Administration. In: Tiers-Monde, tome 18, n°72, 1977. p. 902
Investigation of the Interface Fracture during Debonding between FRP and Masonry
No full textThe masonry-FRP interface fracture is a topic of considerable research interest due to the heterogeneity of the masonry subgrade. The size of the material
inhomgeneity associated with the presence of mortar joints is significant compared with the length scale of fracture process. In this paper, the results of an experimental
investigation into the shear debonding of FRP sheets from brick, mortar and masonry blocks are reported. The test procedures (Ali-Ahmad et al. 2006,2007) developed
previously for obtaining the FRP-concrete cohesive fracture response are applied to study interface debonding from the three substrates. During each test, spatially continuous measurements of the surface strains on the FRP and masonry are obtained using an optical technique known as digital image correlation. The interface cohesive fracture response of FRP-brick and the FRP-mortar interfaces are obtained from the results of the strain analysis. The interface fracture energy associated with the FRPmortar
interface is shown to be significantly smaller in magnitude than that of the FRP-brick interface. The contributions of the mortar and the brick to the overall load response of the masonry are analyzed using the cohesive material response of the FRP-brick and the FRP-mortar interfaces. It is shown that complete debonding is achieved at the FRP-mortar joint while the FRP is still attached to the bricks on either side of the joint. The cohesive crack front stretches across the fully debonded mortar joint before the cohesive crack completely crosses the joint. The local debonding at the mortar joint produces stresses higher than those associated with the main cohesive crack front in the brick-FRP interface close to the joint, thereby accelerating the crack advance
Direct determination of cohesive stress transfer during debonding of FRP from concrete
No full textInterface cohesive stress transfer between FRP and concrete during debonding is typically obtained using
measured surface strains on the FRP, along the direction of the fibers. The cohesive material law is derived under a set of assumptions which include: (a) the bending stiffness of the FRP laminate is insignificant with respect to that of the concrete test block; (b) the strains in the bulk concrete produced by debonding are negligible, thus concrete substrate can be considered rigid; (c) there is stress transfer between FRP and concrete through the FRP–concrete interface which is of zero thickness; and (d) the
axial strain in the FRP composite is uniform across its thickness. In this paper, a test procedure for directly
obtaining the through-thickness strains in the FRP and the concrete substrate during cohesive stress transfer associated with debonding is presented. The displacement and strain fields are measured on the side of a direct-shear specimen with the FRP strip attached on the edge. Based on the experimental results, the influence of the assumptions which have been introduced to determine the cohesive law is discussed. Within the stress transfer zone there is a sharp gradient in the shear strain. The location of
the interface crack within the stress transfer zone and the cohesive stress transfer during the propagation
of the interface crack are determined
Phytoplankton diagnostic pigments from HPLC from samples collected on R/V Endeavor cruise EN614 in the tropical North Atlantic during May 2018
No full textDataset: HPLC PigmentsPhytoplankton diagnostic pigments from HPLC from samples collected on R/V Endeavor cruise EN614 in the tropical North Atlantic during May 2018. Note: these data are also available through NASA's SeaBASS repository at https://seabass.gsfc.nasa.gov/archive/COLUMBIA_U/subramaniam/LAMONT_ATL/may18atl/archive
For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/769601NSF Division of Ocean Sciences (NSF OCE) OCE-173712
Investigation of sub-critical fatigue crack growth in FRP/concrete cohesive interface using digital image analysis
No full textThe cohesive stress transfer during the sub-critical crack growth associated with the debonding of FRP from concrete under fatigue loading is experimentally investigated using the direct shear test set-up. The study focused on high-amplitude/low-cycle fatigue. The fatigue sub-critical crack growth occurs at a load that is smaller than the static bond capacity of the interface, obtained from monotonic quasi-static loading, and is also associated with a smaller value of the interfacial fracture energy. The strain distribution during debonding is obtained using digital image correlation. The results indicate that the strain distribution along the FRP during fatigue is similar to the strain distribution during debonding under monotonic quasi-static loading. The cohesive crack model and the shape of the strain distribution adopted for quasi-static monotonic loading is indirectly proven to be adequate to describe the stress transfer during fatigue loading. The length of the stress transfer zone during fatigue is observed to be smaller than the cohesive zone of the interfacial crack under quasi-static monotonic loading. The strain distribution across the width of the FRP sheet is not altered during and by fatigue loading. A new formulation to predict the debonding crack growth during fatigue is propose
Indoaleyrodes David & Subramaniam
No full text68. Indoaleyrodes David & Subramaniam I. glochidioni Martin & Carver Paratypes, Australia: Queensland, Great Keppel Island, 2.vii.1991, (J.J. Bruhl & G.N. Batianoff), ex: Glochidion lobocarpum, B.M. 1998-51 (2 slides). Australia: Queensland, 50 km S. of Bowen, 20.iv.2001, (P. De Barro 76), ex: Glochidion sp. I . laos (Takahashi) Paratypes: India: Coimbatore, 25.iii.1967, (B. V. David), ex: Morinda tinctoria, B.M. 1972- 24 (2 slides). India: Madras, 6.i.1972, (B. V. David), ex: Morinda tinctoria, 3/72, (4 slides). I. pseudoculatus Martin Paratypes, Papua New Guinea: Morobe Province coast, Buso, 8.x.1979, (J.H. Martin 2674), ex: Syzygium sp. (4 slides).Published as part of Manzari, Shahab & Quicke, Donald L. J., 2006, A cladistic analysis of whiteflies, subfamily Aleyrodinae (Hemiptera: Sternorrhyncha: Aleyrodidae), pp. 2423-2554 in Journal of Natural History 40 (44 - 46) on page 2510, DOI: 10.1080/00222930601121890, http://zenodo.org/record/523048
FRP-Masonry Debonding: Numerical and Experimental Study of the Role of Mortar Joints
No full textFiber-reinforced polymers (FRP) composites are used as supplementary reinforcement to increase the in-plane shear capacity or to provide out-of-plane load-carrying capability of masonry walls and to modify the collapse mechanism in arches and vaults. In these applications, the efficiency of load transfer is limited by the debonding of FRP from the masonry substrate. In this paper, the debonding mechanism of FRP-masonry is experimentally studied. Experimental procedures and test specimens are designed to investigate the progressive debonding of FRP from brick and mortar substrates and relate it to the response obtained from the FRP-masonry interface. Surface displacements during debonding are obtained using digital image correlation. A one-dimensional numerical model is developed for predicting the fracture behavior along the FRP-masonry interface using the cohesive fracture parameters from the brick and mortar interfaces obtained from the computed strains
VISIBLE/ULTRAVIOLET SPECTROSCOPY OF VIBRATION-VIBRATION (V-V) PUMPED CARBON MONOXIDE EXCITED BY A Q-SWITCHED CO LASER
No full text W. Urban, J.-X. Lin, V.V. Subramaniam, M. Havenith, and J.W. Rich, Chem. Phys. 130. 389 (1989).Author Institution: Department of Mechanical Engineering, The Ohio State University; Laboratoirc E.M2.C., UPR 288 C.R.N.S. at Ecole Centrals Paris; Department of Mechanical Engineering, The Ohio State UniversityAn electric discharge CO laser, wall-cooled by liquid nitrogen, is Q-switched by an intracavity chopper. Pulsed output on the fundamental band of 3 watts average power is obtained, with on the component forced by laser-induced cascade. This technique is an extension of the method previously reported by Urban et al(1). The laser is used to excite pure CO, as well as CO/Ar and mixtures, in a flowing-gas absorption cell. Molecular vibrational modes are thereby maintained in a state of extreme V-V pumped disequilibrium. Electronic state emission from CO and various reaction products is being used to infer V-V and V-E energy transfer channels, as well as chemical reaction mechanisms. Further developments of a kinetic model previously used for experiments of this type(1) will also be discussed
An Understanding of the Width Effect in FRP–Concrete Debonding
No full textThe scaling of the ultimate load in fibre-reinforced polymer (FRP)–concrete debonding with the relative width of the FRP is experimentally investigated in this paper. Shear debonding tests are performed to evaluate the cohesive stress transfer between the adherents during the interface crack growth which produces debonding. Concrete specimens with two different widths and different widths of FRP are used in the experimental programme. The nominal stress at debonding increases with the FRP-to-concrete width ratio. For a given width of FRP composite sheet, lower debonding stress is obtained from concrete specimens with a larger width. The strain distribution on the FRP and concrete free surface at different stages of debonding was determined using a full-field optical technique known as digital image correlation. The contribution of the two factors, the boundary effect and the restraint from the surrounding concrete, was studied from the measured strain distribution. The strain distributions across the FRP composite sheet and the concrete within the cohesive stress transfer zone associated with the interface crack are shown to be very inhomogeneous. A region of constant width associated with high shear strains is found at the edge of the FRP sheet during the entire debonding process. The increase in the ultimate nominal stress at debonding is shown to be due to the decrease in the proportion of the total width of the FRP occupied by the edge region. It is shown that the boundary region within the FRP is of a fixed width. The width of concrete close to the edge of the FRP involved in stress transfer, however, increases with the width of FRP. It is established that when the FRP-to-concrete width ratio is smaller than 0.5, the level of restraint from concrete increases with the FRP width
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