Portion Of Column Research Articles

Double skin rubberized steel fiber mixed composite column

Concrete-filled steel tubular (CFST) columns provide a number of structural advantages, such as high strength and fire resistance, good ductility, and huge energy absorption capabilities. ANSYS is used to investigate the structural performance of a double skin rubberized steel fiber mixed composite column. The column incorporated concrete's compressive strength as well as steel's tensile strength. The performance of rubberized steel fiber mixed concrete is initially assessed. To improve the damping property and stop the vibration, 20mesh crumb rubbers are employed. Crumb rubbers are substituted in various proportions (5 percent, 10%, 15%, and 20%) with fine aggregate. Steel fibers are used at a 0.75 percent concentration to reduce fracture diffusion and to sustain dynamic and static loads. Compressive strength, splitting tensile strength, and flexural strength tests are all performed. Crumb rubber replacement enhances compression strength, split tensile strength, and flexural strength up to 15%, after which the strength tends to decline, therefore it is determined that crumb rubber replacement up to 15% and steel fiber 0.75 percent can be used. Various types of columns are modelled and their structural performance loads are studied Hexagonal in square (HS), Hexagonal in circular (HC), and Hexagonal in Hexagonal (HH). When compared to traditional reinforced concrete (RC) columns, CFST columns are more cost-effective, faster to construct, and can handle higher loads. ANSYS is used to apply an axial load on the above columns and analyze them (finite element method). Finally, the outcome is compared to various column portions. When compared to HS and HH columns, the HS column has double the weight bearing capability.

Numerical Prediction of the Seismic Behavior of Reassembled Columns in Ancient Structures: An Anastylosis Model for the Temple of Apollo Pythios in Gortyn (Crete)

The Temple of Apollo Pythios in Gortyn (Crete, Greece) dates back to the mid-7th century BC. The temple underwent several transformations and an ultimate destruction over time that resulted in the current remains of a Roman colonnade composed of six fragmented stone columns lying on the ground within the naos. In addition, the region was struck by several earthquakes which contributed to the various changes. The analysis of the fragments composing the column portions and their geometric features provided a possible outline for their standing repositioning. Based on the current seismic hazard of the region, a predictive numerical model of the colonnade in the anastylosis conditions suggested the need for proper connections between the fragments and the bases to ensure their overall conservation as a compound structure. The comparison of various configurations of intervention and the simple superimposition of the fragments also provided details on the accomplishment of minimal and compatible solutions.

Behavior of Eccentrically Loaded Slender Concrete Columns Reinforced with GFRP Bars

This paper presents an experimental investigation on the behaviour of concrete columns reinforced with glass fibre reinforced polymers GFRP bars under concentric and eccentric loads. Six RC column specimens have been considered in the experimental tests with a cross section dimension of (135 mm × 135mm) at the middle portion of columns and (250 mm × 135 mm) (width ×depth) at the corbel with a total length of 1150 mm with the length between corbels (middle part) was 710 mm. Three specimens have been represented the reference specimens which are reinforced with steel bars and the other three were reinforced with GFRP bars. Tow variables have been considered in the experimental tests: the type of reinforcement (GFRP and steel) and the eccentricity ratio (e/h). All columns have been subjected to different values of eccentricity ratio (e/h): 0, 0.5, and 1. It has been concluded that the ultimate load capacity of columns reinforced with GFRP bars decreases by about 27.13% and 94.67% compared to columns reinforced with steel bars under eccentricity ratios (e/h=0) and (e/h =0.5), respectively. Whereas, ultimate load increases by about (4.79%) for the columns reinforced with GFRP bars compared to columns reinforced with steel bars at eccentricity ratios (e/h=1). The result have also shown that all specimens that have been subjected to eccentricity ratio (e/h > 0) failed by compression failure.

Spatial distribution of nutrients associated with water masses in the Tubarão Bight (20°S–22°S), Brazil

The bathymetry in the region of the Tubarão Bight is complex. When associated with the morphological variations in the continental shelf and the presence of the Vitória-Trindade Chain, peculiar physical characteristics capable of modifying the hydrodynamic flow and the distribution of water masses on the continental shelf appear. Moreover, the presence of cyclonic eddies and the upwelling process reinforce the importance of this region from a physical and biological perspective, especially related to the input of nutrients to the euphotic zone. This study aimed to analyze the spatial distribution of nutrients and its relationship with water masses (Coastal Water (CW), Tropical Water (TW), South Atlantic Central Water (SACW), Antarctic Intermediate Water (AAIW), and Upper Circumpolar Deep Water (UCDW)). The spatial distribution of nutrients was calculated via extended optimum multiparameter analysis using conservative (temperature and salinity) and nonconservative (dissolved oxygen (O2), nitrate (NO3−), silicate (SiO2), and phosphate (PO43−)) parameters. In this region, the presence and distribution of water masses are conditioned by the dynamics and variability associated with continental discharge, the Brazil Current, and local hydrodynamics. The spatial-temporal distribution of nutrient concentrations was strongly related to the distribution of water masses and the processes related to regeneration, coastal upwelling, erosion of the upper thermocline, and cyclonic eddy presence. As a result, on the continental shelf, the highest concentrations of SiO2 and dissolved O2 occurred in the water column portion occupied by CW and TW, whereas NO3− was associated with SACW. Offshore, the highest nutrient concentrations (SiO2, NO3−, and PO43−) were related to intermediate water masses (AAIW and UCDW). Furthermore, the highest concentrations of dissolved O2 were associated with TW and AAIW as a result of ocean-atmosphere interactions and formation processes.

Experimental and Numerical Investigation of Transverse Circular Holes on Load-Carrying Capacity of RC Columns

Transverse Circular Holes (TCH) are provided in structural members for accommodating various utility services, which results in a reduction in the load-carrying capacity of the members. The present study has been carried out to investigate the effect of transverse hole in reinforced concrete column and to compensate for the strength in lieu thereof. The performance of specimens with TCH having an area greater than 15% of column width and located in the upper third portion of columns, under axial loads was evaluated. Seven types of specimens tested with different solutions for columns with TCH were evaluated and compared with control specimens. It was concluded that axial strength of the specimen could be reduced by 21% due to TCH. Results from the experimental study showed that up to 13% strength recovery is possible using various solutions adopted in this investigation. Furthermore, a finite element model in ABAQUS software was developed for the analysis of columns to study the ultimate capacity, stress–strain curves and crack patterns. The experimental results of cracks and stress–strain curves obtained from ABAQUS were compared. Several factors like available area, economy, and ease of construction govern the choice of a suitable method. It was found that increasing column area to accommodate a TCH is the most effective option among all the tested options.

Behavior of Monotonic Loading for Glass Fibre based High Performance Concrete in External Beam-Column Joint using ANSYS. Analysis

Strength, ductility of structures differ primarily on appropriate detailing of. beam column joints need a vital role in the structural reliability of the structures given with appropriate stiffness and ultimate strength to maintain the loads transmitted from beam and column. Beam column joints defined as the reinforced concrete buildings, in which portion of columns and beams having their intersections. Although these forces greater than these are affected during earthquakes, joints are relentlessly damaged. As far as earthquake is affected, research on beam-column joint is essential. In HPC, these materials with admixtures are meticulously designated and proportioned to produce very high early, ultimate strengths and durability away from conventional concrete. The admixtures like flyash, silicafume, ground granulated blast furnace slag (GGBFS), which are combined with its strength and durability and boost its marketability as a natural friendly product. The most important purpose of the present study is to investigate the performance of high performance reinforced beam-column joints (replacement of cement with GGBFS). Ground granulated blast furnace GGBFS is employed as a partial replacement of cement with glass fibre and super plasticizer is applied to accomplish required workability. In this study, a evaluation of control specimen and specimen of beam column joint with 7.5% GGBFS and 0.3% glass fibre replacement intended as per IS 456:2000 and IS 13920:2016. Also, to ascertain the performance of beam-column joints subjected to monotonic loading for high performance concrete employing with Ground Granulated Blast Furnace Slag (GGBFS) and glass fibre.

Prediction of Corner Columns’ Load Capacity Using Composite Material Analogy

There are numerous reasons for which concrete has become the most widely used construction material in buildings, one of them being its availability in different types, such as fiber-reinforced, lightweight, high strength, conventional and self-compacting concrete. This advantage is specially realized in high-rise building construction, where common construction practice is to use concretes of different types or strength classes in slabs and columns. Columns in such structures are generally made from concrete which is higher in compressive strength than the one used in floors or slabs. This raises issue of selection of concrete strength that should be used for estimating column capacity. Current paper tries to address this issue by testing nine (09) sandwich column specimens under axial loading. The floor concrete portion of the sandwich column was made of normal strength concrete, whereas column portions from comparatively higher strength concrete. Test results show that aspect ratio (h/b) influences the effective concrete strength of such columns. A previously adopted methodology of composite material analogy with some modifications has been found to predict well the capacity of columns where variation in floor and concrete strength is significant.

Responses of microbial community to pH stress in bioleaching of low grade copper sulfide

The microbial diversity and dynamics in the leachates and on the ore surfaces of different depth of the column were analyzed during bioleaching of low grade copper sulfide at different pH, after inoculation with the same inoculum containing mesophiles and moderate thermophiles. The results indicate that low pH was beneficial to enhance copper extraction. The highest copper extraction (86%) was obtained when pH was controlled at 1.0–1.5. The microbial structures on the ore surfaces were independent of community structures in the leachate, even at the top portion of column. Microbial richness and evenness increased with decreasing pH during bioleaching. pH had significant effects on microbial community structure in the leachate and on the mineral surface of different depth of the column. Leptospirillum ferriphilum accounted for the highest proportions of the community at most times when pH was operated during bioleaching, especially at the end of run.

The internal wave prediction component of the Integrated Ocean Dynamics and Acoustics Project

The accuracy of ocean sound propagation modeling depends on properly representing the environment. The water column portion of this has phenomena and features that are time- and space-dependent, covering a huge range of scales. Nonlinear internal gravity waves (nonlinear internal waves, NIW) in shallow areas are important features that are moving, evolving and anisotropic, and whose effects can be handled properly only with 3D sound modeling. Thus, 3D NIW field predictions would be needed for comprehensive modeling. One challenging part of our project to make acoustic condition forecasts from available data involves making this 3D NIW field prediction using data-assimilating regional models that do not faithfully handle NIW. Our methods for extracting internal tide signals from the models, analyzing their propagation into regions where they transform in reality to NIW (but not in the models), and predicting NIW conditions in these regions are explained here. Outstanding challenges such as how to parameterize internal-tide coupled mode propagation on slopes and how to model highly nonlinear crossing NIW groups will be presented. The question of what constitutes an effective NIW prediction for acoustic purposes will be addressed.

Effect of Fibres on Beam Column Joint Failure

Concrete is one of the most resourceful and environmental friendly building materials. It can be cast to fit any structural shape from a cylindrical water storage tank to a rectangular beam, slabs and column in a high-rise building. In RC buildings, portions of columns that are common to beams at their intersections are called beam column joints. Beam-column joints have a crucial role in the structural integrity of the buildings. Review of literature indicates that numerous studies were conducted in the past to study the behaviour of beam-column joints with normal concrete. However, those recommendations are not intended for the fibre reinforced concrete. Some indicates that this material is an alternative to the confining reinforcement in the joint region. So the comparative study of the performance of different fibres in beam column joint has a greater importance and relevance in the field of RCC framed structures. This thesis aims to study the behaviour of beam column joint by evaluating the performance of fibre reinforced concrete. The incorporation of fibres in beam column joint is analysed in this study. The use of different types of fibres such as steel and polypropylene are evaluated.

SURVIVING METAMORPHISM: TAPHONOMY OF FOSSIL ASSEMBLAGES IN MARBLE AND CALC-SILICATE SCHIST

Devonian massive graphitic marble and calc-silicate schist, belonging to the Lower Formation of the Nevado-Filabride Complex of the Internal Zones of the Betic Cordillera, crop out extensively near Aguilas (Murcia, SE Spain). These rocks contain a rich fossil record even though they have undergone Alpine metamorphism and deformation (350–480°C; 2 Kb). In this paper, we focus on the taphonomic characteristics of the fossil assemblages to infer the depositional processes that can be reconstructed even after metamorphism. The most abundant fossils are crinoids, followed by phacelloid colonial rugose corals, brachiopods, cephalopods (ammonoids and orthoceratids), and possible gastropods and benthic foraminifers. Crinoids occur as isolated columnal ossicles, as well as articulated portions of columns (pluricolumnals). One complete calyx was also found. Taphonomically delicate crinoids are preserved in the calc-silicate schist beds. In the massive marble beds, crinoids occur mostly as disarticulated ossicles, but they still bear delicate ornamental features. Some corals preserve external walls. The low degree of abrasion indicates disarticulation of the crinoids due to exposure in the taphonomic active zone (TAZ), but under low-energy conditions. Articulated crinoids are preserved due to catastrophic burial events. The preservation of the fauna allows the differentiation of background versus event biostratinomic processes even after being highly altered by metamorphism.

Chronological vs. physiological age indicators in beef cattle: Effects of the production system and growth promotants

s published in Meat Science from the 2014 CMSA / CMC Abstracts are published in cooperation with the Canadian Meat Science Association / Canadian Meat council and have been subject to the Societies own review process and have not been peer reviewed by the Editorship of the journal In the absence of verifiable chronological age, both dentition and carcass ossification have been used as physiological indicators. Physiological maturity is also important in the determination of meat quality. Changes in production practices may have altered the relationship between chronological age and physiological maturity. A total of 224 steers of known chronological age were allotted to a 2 × 2 factorial arrangement of treatments to determine the effect of production system (calf-fed: CF; yearling-fed: YF) and growth implant (non-implant: NIMP; implant: IMP) on physiological indicators of chronological age. There were significant interactions (P b 0.001) between the production system and the implanting strategies on the frequencies of the carcasses showing ossification in the sacral, lumbar and thoracic vertebral column portions. In the CF, 59% of the NIMP and 2% of the IMP carcasses did not show any evidence of fusion in the sacral portion. In the lumbar portion, none of the NIMP CF showed any ossification (score 0), while most of ⁎ Corresponding author at: Lacombe Research Centre, Agriculture and Agri-Food Canada, 6000 CE fax: 01403 782 6120 E-mail addresses: oscar.lopezcampos@agr.gc.ca, olopezcampos@gmail.com (O. Lopez-Campos). http://dx.doi.org/10.1016/j.meatsci.2014.07.013 0309-1740/© 2014 Elsevier Ltd. All rights reserved. the IMP CF (80%) showed varying degrees of ossification (scores 1–5). In the YF, all the carcasses from the IMP showed advanced ossification ranging from two islands (score 3, 17% and score 4, 15%) to a long fused island on the vertebral cap (score 5, 67%). Sixty six percent of the NIMP YF did not show any osseous formations in the lumbar caps (score 0) and 26% showed a single small island (score 1). The IMP YF (96%) showed ossification in the thoracic portion, while most of the NIMP YF (98%) and both implant groups of the CF (NIMP 100%; IMP 91%), did not show ossification in the thoracic caps. These results support that the physiological maturity of the carcasses might be dramatically impacted depending on the combination of the production system and growth implant strategy. A compendium of descriptors based on dentition and ossification processes at the vertebrae column should be taken into consideration to ensure accurate estimation of chronological age of cattle when birth date is not available.

Comparative Study on Behaviour of Reinforced Beam-Column Joints with Reference to Anchorage Detailing

The ductility capacity, energy dissiaption capapcity and load - deformat ion behaviour of the exterior beam column jo ints constructed with an external anchorage system by provid ing a s mall project ion beyond the column face is evaluated. The evaluation is based on the experimental results of two one fifthe scale exterior bam co lu mn joint specimens tested as part of an extensive experimental program. The control specimen (CS) constructued and detailed as per IS 13920:1993 codal provisions and externally anchoraged specimen (EAS) cast with small projecttion beyond the column face. A s mall axial load was applied to the column port ion of the subasembly and held constant during the test. The free end of the beam was subjected to cyclic load representing a wide range fro m elastic to inelastic loading.By providing an external anchorage system, the reinforcement detailing and concrete placement in the joint region beco me eased and the behavior was better than conventional method of construction. The test results indicate that external anhorage system exhibits excellent behavior in energy dissipation , ductility and load - deformation parameter than for specimens constructed to current design recommendations.

Effect of Constitutive Equations on Dynamic Bend Buckling Analysis of Thin Steel Sheet Hollow Columns

Selecting a suitable constitutive equation which takes account of the precise strain rate sensitivity of the material is, in general, very important for dynamic-crash analyses. Tanimura-Mimura (T-M) model is one of a few constitutive equations which are able to describe the specific characteristics of many ferritic steels that the strain rate sensitivity in flow stress decreases with increasing plastic strain, however, it has not been examined well how the crash analyses are improved when this model is employed. In this paper, both experimental and numerical analyses of dynamic three-points bend test of thin steel sheet hollow column were conducted at the impact velocity of 4m/s in order to evaluate the effectiveness of T-M model. In the numerical analyses, Cowper-Symonds (C-S) model and strain rate insensitive (I-S) model as well as T-M model were employed, and their calculated results were compared with the experimental result. The calculated load-stroke relations by T-M model showed good agreement with the experimental ones over the whole stroke, on the contrary C-S model was in agreement only in the small stroke region. Shape profiles of the buckling portions of columns in the experiment were compared with the simulated results based on each model. The width of the buckling zone was getting smaller in the order of T-M model, I-S model and C-S model, and T-M model was found to give the best agreement with the experiment since its low strain hardening profiles in stress-strain relations at high strain rates promote the localization in the buckling zone. From these results, T-M model can be considered to improve accuracy of numerical simulation, especially in the case that significant strain localization such as buckling occurs.

On magma fragmentation by conduit shear stress: Evidence from the Kos Plateau Tuff, Aegean Volcanic Arc

Large silicic explosive eruptions are the most catastrophic volcanic events. Yet, the intratelluric mechanisms underlying are not fully understood. Here we report a field and laboratory study of the Kos Plateau Tuff (KPT, 161 ka, Aegean Volcanic Arc), which provides an excellent geological example of conduit processes that control magma vesiculation and fragmentation during intermediate- to large-scale caldera-forming eruptions. A prominent feature of the KPT is the occurrence of quite unusual platy-shaped tube pumice clasts in pyroclastic fall and current deposits from the early eruption phases preceding caldera collapse. On macroscopic and SEM observations, flat clast faces are elongated parallel to tube vesicles, while transverse surfaces often occur at ~ 45° to vesicle elongation. This peculiar pumice texture provides evidence of high shear stresses related to strong velocity gradients normal to conduit walls, which induced vesiculation and fragmentation of the ascending magma. Either an increasing mass discharge rate without adequate enlargement of a narrow central feeder conduit or a developing fissure-like feeder system related to incipient caldera collapse provided suitable conditions for the generation of plate tube pumice within magma volumes under high shear during the pre-climactic KPT eruption phases. This mechanism implies that the closer to the conduit walls (where the stronger are the velocity gradients) the larger was the proportion of plate vs. conventional (lensoid) juvenile fragments in the ascending gas–pyroclast mixture. Consequently, plate pumice clasts were mainly entrained in the outer portions of the jet and convecting regions of a sustained, Plinian-type, eruption column, as well as in occasional lateral blast currents generated at the vent. As a whole, plate pumice clasts in the peripheral portions of the column were transported at lower altitudes and deposited by fallout or partial collapse closer to the vent relative to lensoid ones that dominated in the inner column portions. The plate tube pumice proportion decreased abruptly up to disappearance during the emplacement of the main pyroclastic currents and lithic-rich breccias related to extensive caldera collapse at the eruption climax, as a consequence of an overall widening of the magma feeder system through the opening of multiple conduits and eruptive vents, along with fissure erosion, concomitant to the disruption of the collapsing block.

A Tidal Prism Water Quality Model for Small Coastal Basins

A tidal prism water quality model (TPWQM) was developed to provide a tool for government agencies for water quality management of small coastal basins. It simulates physical transport using the concept of tidal flushing, includes one of the most sophisticated representations of eutrophication processes in water column and benthic sediment, and employs an innovative solution scheme that is simple, accurate, and computationally efficient. The predictive capability of the water column portion of TPWQM was demonstrated through successful calibration and validation of the model with extensive data sets collected from Lynnhaven Bay, Virginia. The model's general applicability was examined for four other Virginia coastal basins. One value (0.3) of the returning ratio, the only calibration parameter for physical transport, is applicable to all five coastal basins and probably would be adequate for other Virginia coastal basins without further calibration. The values of kinetic parameters determined for Lynnhaven Bay are applicable to at least two of the other four coastal basins. The model underpredicts chlorophyll-a, total carbon, and total phosphorus in two of the tested basins, which is more likely the result of underpredicted nonpoint source loads than the inaccuracy of the kinetic coefficients. Therefore, the set of kinetic coefficients may be applicable to all the Virginia coastal basins with basin-specific refinement in the estimation of nonpoint source loads.

Evolution of the initially ordered structure in a magnetic fluid film during a thermal cycle

A hexagonal ordered structure of magnetic columns, which results from an agglomeration of magnetic particles, is obtained in a magnetic fluid film when a magnetic field is applied perpendicularly to the film surface. The evolution of the initially ordered structure in the magnetic fluid film during the heating and cooling process is investigated under a given magnetic field. For the heating process, the columns remain unchanged until the temperature exceeds a critical temperature. As the temperature is further increased, column particles start to disperse into the liquid carrier. As a result, portions of columns disappear. As the temperature continue to rise, the ordered structure changes to a disordered column state, or even a monodispersed state. On the other hand, when the temperature is lowered, the magnetic particles in the carrier condense out of solution and finally an ordered structure of columns is achieved. However, this structural evolution during a thermal cycle is irreversible.

Behavior of High-Strength Concrete Corner Columns Intersected by Weaker Slabs with Different Thicknesses

This paper reports the findings of a research project undertaken at the University of Melbourne (Australia) to study the failure mechanism of sandwich columns consisting of high strength concrete (HSC) column portions and a normal strength concrete (NSC) slab under axial compressive loading. The aims were to study the effects of h/c aspect ratio and column rectangularity on effective compressive strength of a sandwich HSC column-NSC slab joint and develop a theoretical model to predict the failure of corner column-slab joints with h/c ratios greater than 0.25.

Monotonic and cyclic loading models for panel zones in steel moment frames

This paper presents the development of analytical models to predict the elastic and inelastic response of the panel zone portion of columns in steel moment resisting frames. In many practical cases, the panel zone can dominate the inelastic response of a moment frame, and accurate panel zone models are needed to realistically predict overall frame performance. Similar to previous models, the newly proposed models are based on the concept of representing the panel zone as a nonlinear rotational spring. These new models build on previously developed models, and introduce a number of features and refinements that show better correlation with available experimental data. The model for monotonic loading is based on quadri-linear panel zone moment–deformation relations. In this model, both bending and shear deformation modes are considered. The model proposed for cyclic loading is based on Dafalias' bounding surface theory combined with Cofie's rules for movement of the bound line. Additional modifications are suggested to the cyclic loading model to account for the influence of a composite floor slab on panel zone response. Extensive comparisons with experimental data are presented.

Vehicle vibration simulator

A vehicle vibration simulator to simulate occupant exposure to vibration in a motor vehicle includes a reaction mass, a seat portion, a seat actuator between the reaction mass and the seat portion for providing at least one degree of vibration freedom, a steering column portion, a steering column actuator between the reaction mass and the steering column portion for providing at least one degree of vibration freedom, a floorpan portion, a floorpan actuator between the reaction mass and the floorpan portion for providing one degree of vibration freedom, the seat actuator, steering column actuator and floorpan actuator being actuated independently and/or simultaneously to simulate occupant exposure to vehicle vibration.