Open Section Research Articles

Rationalization of cross-sections of the composite reinforced concrete span structure of bridges with a monolithic reinforced concrete roadway slab

The article presents the developed rationalization technique of composite steel reinforced concrete sections with steel open section beams based on the criterion of equal strength of the section elements that are extremely distant from the neutral line. Algorithms for search for geometric parameters of a composite section limited to a certain range of values are implemented to achieve the equal strength condition. The dimensions of the individual elements which are parts of the cross-section are obtained from the condition of the constant ratio of the distances from the neutral axis to the extreme concrete and steel fibers. The numerical methods were used for calculation of continuous three-span composite reinforce concrete bridge. The technique implements the steps of bridge construction, taking into account the contact yield of the composite section, the redistribution of forces between the elements, and the effect of elastic-plastic and rheological properties of materials. The generalized kinetic curve was utilized for evaluation of concrete creep together with the phenomenological equations for the development of deformations based on a colloid-chemical representation of the mechanism for long-term concrete deformation. The proposed methodology is implemented in the LIRA-SAPR software package based on the Building Information Model Technology (BIM) and the Finite Element Method (FEM).

High‐efficiency gravel longshore sediment transport and headland bypassing over an extreme wave event

AbstractGravel beaches are common throughout the high latitudes, but few studies have examined gravel transport rates, in particular at high energy levels, and no studies have quantified gravel transport around headlands. Here, we present the first complete sediment budget, including supra‐, inter‐ and sub‐tidal regions of the beach, across multiple headland‐separated gravel embayments, combined with hydrodynamic observations, over an extreme storm sequence, representing at least a 1‐in‐50‐year event. Unprecedented erosion was observed (~400 m3 m−1, −6 m vertical), with alongshore flux of 2 × 105 m3, equivalent to annual rates. Total system volume change was determined to the depth of closure and then used to calculate alongshore flux rates. Alongshore wave power was obtained from a wave transformation model. For an open section of coastline, we derive a transport coefficient (CERC formula) of KHs = 0.255 ± 0.05, exceeding estimates in lower‐energy conditions by a factor of 5 or more. We apply this coefficient to rocky segments of the shoreline, determining rates of headland bypass from 0 to 31% of potential flux, controlled by headland extent and toe depth. Our results support the hypothesis that gravel is transported more efficiently at higher energy levels and that a variable rate or threshold approach may be required. Complete coverage and varying morphology make this dataset uniquely suited to improving model predictions of gravel shoreline change. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.

Entrepreneurship Development In India – Problems And Prospects


 - Business visionaries recognize a fundamental development in making and adding to the economy of a nation and expressly truly coming to fruition scene where there are rich open sections for movements to misuse the available resources and begin forceful undertakings. Regardless, the move of business in all countries and in all bits of any country isn't unpredictable even, as we see more stars ascending out of made countries. The present paper investigates various bits of business improvement in an economy and its activity in the money related development of a country. Another Catch 22 exists moreover as growing number of jobless masses, searching for provider's activity and incognizant about the wide open entryways for longing calling by honorableness of the nonappearance of heading about business undertaking. In a huge part of the creation countries including India, business has not found the spot toward the path educational program.

Eco-Friendly Snow Melting Systems Developed for Modern Expressways

Abstract This study presents environmentally friendly snow melting methods utilizing electric heating cables, ground source heat pumps, tunnel water heat, solar-assisted electric heating cables, and boilers that have been developed and tested at several expressway sections in South Korea since 1996. Compared with a conventional winter maintenance practice based on deicing or anti-icing chemicals, these snow melting systems have little environmental impact (i.e., eco-melting) and are useful in clearing away snow and preventing ice formation promptly without causing long and frequent traffic hold-ups. A comparative evaluation on the eco-melting systems is conducted to characterize their construction and operation features, and the snow melting performance of each system is validated at full-scale test sites under various winter weather conditions. Also, cost analyses are conducted based on the data collected from the field experiments to determine the affordability of each system. Finally, five types of expressway sections (hi-pass toll lane, regular toll lane, an open section between tunnels, curved road, and bridge) that are vulnerable to traffic accidents during winter are prioritized based on three factors (safety, affordability, and environment) for the optimum deployment of eco-melting systems on modern expressways.

Rescattering effects in antiproton-induced exclusive J/$ \psi$ and $ \psi^{{\prime}}_{}$ production on the deuteron

On the basis of the generalized eikonal approximation we study the exclusive reactions $\bar p d \to J/\psi\, n$ and $\bar p d \to \psi^\prime\, n$ in vicinity of the thresholds for charmonium production on a free proton target. It is shown that the rescattering of the incoming antiproton and outgoing charmonium on the spectator neutron leads to a depletion of the charmonium production at low- and to an enhancement at high transverse momenta. This is in qualitative agreement with previous studies of hard proton knockout in proton-deuteron collisions. We analyze different physical sources of uncertainty which may influence the extraction of the total charmonium-neutron cross section. The color transparency effect for the incoming $\bar p$ largely compensates the influence of charmonium rescattering both at low and high transverse momenta. Different choices of the deuteron wave function lead to significant uncertainties at high transverse momenta. As an outcome of the calculations of charmonium production, we also provide predictions on the production of open charm hadrons due to the dissociation of the charmonium on the neutron. It is shown that the open charm production cross section is proportional to the total charmonium-nucleon cross section and quite stable with respect to the variation of other parameters of the model. We thus suggest that open charm channels are most suited for future studies of charmonium-nucleon interactions at PANDA with a deuteron target.

Mode‐based Beam and Connection Analysis of Frames

ABSTRACTMajor steel structures are commonly constructed as frames or trusses. The connections between its beams and columns have a crucial influence on the global behaviour. However, a detailed assessment of the joints is often neglected with rough simplifications, which may lead to poor results. On the other hand, if performing a detailed assessment it is a time‐consuming task requiring special expertise. Consequently, the idea stressed in this paper is a novel approach on how to analyse thin‐walled steel frames including a detailed assessment of both the joint and beam mechanics.The approach is based on a transformation from standard degrees of freedom into a displacement‐based mode formulation. Furthermore, this transformation reduces the total number of degrees of freedom to be computed for advanced joints and beam elements. All this is achieved by adopting an advanced beam element formulation as well as introducing the idea of a ‘joint element’ formulated by finite shell elements. One of the main advantages of this idea is a general formulation of the joint, which makes it valid for many beam‐to‐column configurations. Furthermore, beam members can either be closed or open sections due to the adopted advanced generalised beam theory. Furthermore, a detailed analysis of the joint element itself is also achieved by this approach. Finally, an increased efficiency is achieved due to reduction of the total amount of degrees of freedom of the advanced model, and a new in‐depth knowledge of the joint behaviour is gained from this approach as well, due to the displacement‐based mode formulation.

Dual-Loop Antenna for 4G LTE MIMO Smart Glasses Applications

A dual-loop antenna with massive-input–massive-output (MIMO) operation within the fourth-generation Long Term Evolution (LTE) bands for smart glasses applications is proposed. The 2 × 2 MIMO antenna array is formed by converting the glasses frame into two symmetrical single-loop antenna structures and using the glasses “temple” region as a common ground plane. For each single-loop antenna to excite four resonant modes so that it can yield a desirable −6 dB impedance matching across the desired low band (LB), 824–960 MHz, and high band (HB), 1710–2690 MHz, of LTE operations, a simple matching circuit is loaded into the open section of the loop antenna. Further measurements show good efficiency and isolation across the LB and HB for the dual-loop antenna. Finally, the calculated envelope correlation coefficient and ergodic channel capacity of the 2 × 2 MIMO antenna are also discussed.

Member moment capacity of complex-shaped aluminium mullions under wind suction loading

Unitized curtain wall systems made of aluminium frame infilled glass panes are commonly used to form the building envelopes in many buildings. The vertical framing members of such systems known as mullions are extruded aluminium sections with complex geometries. These mullions must transfer the wind load acting on the building envelope to the main structural system. This paper presents a detailed numerical study on the member moment capacities of long span mullion sections subject to wind suction loading. Validated finite element models of the mullions developed to predict their section moment capacities were extended to predict the member moment capacities. The procedures adopted in developing the finite element models and the analysis results are given in this paper. Mullions of different cross-section geometries with varying member slenderness used in both the captive and structural glazing systems were considered. In addition, the performance of open and hollow mullion sections was investigated. Lateral restraints provided by the glass panels to the mullions were simulated in the models while the effect of providing lateral restraint at the mid-span of the mullion through bracing was also investigated. The finite element analysis results were compared with the predicted capacities of Aluminium Association Design Manual and Eurocode 9 Part 1-1 design rules and suitable recommendations were made in relation to their applicability for mullion sections. Improved mullion sections reinforced with cold-formed steel stiffeners were proposed and their potential use in real world applications was discussed.

Shape Design Enhancement of Pultruded FRP Profiles for Structures Ancillary to Masonry Constructions

The historical building heritage, monumental, civil and industrial has highlighted, especially in the last decade, the high vulnerability with respect to horizontal actions. The need to design stable and strong structural systems with respect to the stresses acting in various directions has oriented research to develop lightweight technologies for structural systems, independent or ancillary, with reduced mass to mitigate the consequent applied load. In this scenario all-FRP (Fiber Reinforced Polymers) systems can be a valid alternative for new constructions and / or structural reinforcement. The scenario described above, highlights the importance of developing innovative technologies suitable for the functional and structural improvement of the existing buildings. It is necessary to define an innovative approach aimed at identifying an ad-hoc profile for the FRP pultruded profiles (currently referring to the steel shapes), which allows to capitalize the performance capabilities, limiting the main defects related to low shear stiffness of FRP pultruded material. This research analyses how the shape enhancement of the cross sections, with shape redraw, allows to increase the structural performances of FRP pultruded profiles. Experimental data of previous research on buckling behaviour of different open cross section profiles, narrow and wide flanges, have been analysed and validated by numerical approach and compared with new strengthened shapes.

Lake sedimentation as an agent of postglacial transformation of interfluves and fluvial landscapes of the Borisoglebsk Upland, Central European Russia

Abstract. Borisoglebsk Upland is considered an example of a secondary upland plain in the marginal zone of the last Middle Pleistocene glaciation. Moraine hills and kames were reworked by glaciofluvial processes and incised by small fluvial forms later. Its postglacial surface drift cover is regularly defined as an undivided complex of mantle loams of dominantly subaerial origin with characteristic cryogenic features and remnants of paleosols. However, some previous studies suggest that lake sedimentation played an important role in the postglacial history of the Borisoglebsk Upland. This paper presents results of a detailed investigation of postglacial sedimentary cover of the eastern part of the Borisoglebsk Upland aimed to reconstruct the co-evolution of surface deposits, soil cover and geomorphic landscapes since degradation of the last Middle Pleistocene glaciation about 150 ka (MIS-6). The study is essentially based on a comprehensive lithological, pedological and geocryological description of postglacial deposits in cores (hand or machine-driven) and open sections, systematic sampling for grain size analysis and selective sampling for 14C absolute dating and monoliths structural examination. The results indicate that most of the surface drifts in this feature consists of stratified lacustrine deposits. Their Late Pleistocene age is stratigraphically confined by the underlying paleosols and incorporated peats of the Mikulino interglacial age (MIS-5) and several organic-rich layers within the lake sequence 14C dated to the Middle Valdai interstadial (MIS-3). Overlying mantle loams and colluvial deposits with cryogenic features and low organic matter content those facially substitute lacustrine sediments were attributed to the Late Valdai stadial (MIS-2). After the Mid-Holocene stabilization, relatively thin colluvial cover identified by the increased amount of organic matter also deposited. We conclude that lacustrine sedimentation is the primary Late Pleistocene agent that transformed the initial glacial topography and most characteristic type of lithodynamics of the eastern Borisoglebsk Upland.

Further improvements in sorting grids for the crustacean trawl fishery off the Southern coast of Portugal

Bottom-trawl fishing for crustaceans off the Portuguese south and southwest coasts is a very important segment of the Portuguese fishing fleet, where annual rates of discarding have ranged from approximately 38% to as much as 70% of the total catch. Past experiments to address this problem encompassed the testing of different codend mesh sizes and configurations, square mesh windows and rigid grids to enhance species and size-selectivity. While the use of a Nordmøre grid has proved quite efficient in separating out blue whiting (Micromesistius poutassou), it also led to some losses of the two main crustacean target species, Norway lobster (Nephrops norvegicus) and rose shrimp (Parapenaeus longirostris). The present study addresses that limitation by using a modified grid with 20 mm bar spacing and two open sections, designed with the purpose of separating fish and crustacean species into upper and lower codends. Good separation was achieved, with about 80% of the blue whiting (in number) directed towards the upper trawl section and caught in the upper codend, while a similar percentage of Norway lobster was caught in the lower codend. The grid bars had 50% retention for Norway lobster at 34.1 mm carapace length. The results herein will enable this gear configuration to be fine-tuned with regard to codend mesh sizes and bar spacing, so as to optimize both retention of Norway lobster and exclusion of blue whiting. For example, compared to using the minimum 70 mm diamond mesh size, using an 80 mm diamond mesh upper codend would reduce Norway lobster catch weight by just 1.6% but reduce the number of blue whiting caught by 42%.

Compressive instability of open section nanocomposite struts using a layerwise theory

The application of carbon nanotubes (CNTs) to improve postbuckling characteristics of T-section nanocomposite strut is the subject of this research. A solution procedure according to the layerwise theory along with the first-order shear deformation theory (FSDT) by taking into account the von Karman geometrical nonlinearity is proposed. Nonlinear governing equations are developed in regard to the minimum total potential energy principle, and solved by the aid of the Rayleigh–Ritz method in conjunction with Newton–Raphson method. A comprehensive parametric study is conducted to provide an insight into effects of CNT volume fraction and dispersion, geometrical parameters and boundary conditions on the bifurcation points and paths, in-plane displacement, normal stress and strain, and bending moment of T-section nanocomposite struts. A three dimensional finite element analysis using the ABAQUS commercial software is carried out to verify the obtained results, which shows close agreement. Results indicate that dispersion of CNTs plays a dominant role in bifurcation behavior of nanocomposite struts. The results also show that volume fraction of CNTs has a significant effect on the load-carrying capacity of open section nanocomposite struts. The results of this research shed light into using ultra-high-strength and light-weight open section nanocomposite struts for civil and aerospace applications.

Experimental and numerical investigations of hot-rolled austenitic stainless steel equal-leg angle sections

The present paper reports a thorough experimental and numerical study on the cross-section behaviour and resistances of hot-rolled austenitic stainless steel equal-leg angle section structural members. The experimental programme was performed on a total of five different angle sections, and involved ten stub column tests and ten laterally restrained 4-point bending tests about the cross-section geometric axes (parallel to the angle legs), together with measurements on material properties and initial local geometric imperfections. The testing programme was followed by a systematic finite element simulation programme, where the developed numerical models were firstly validated against the experimentally derived results and then employed to carry out parametric studies for the purpose of generating further structural performance data over a broader range of cross-section dimensions. The numerically derived results were then employed together with the test data to assess the accuracy of the established design rules for hot-rolled austenitic stainless steel equal-leg angle section stub columns and beams given in the European code. The results of the assessment revealed an overly high level of conservatism and scatter of the European code in predicting cross-section capacities of hot-rolled austenitic stainless steel equal-leg angle section stub columns and beams, which can be mainly attributed to the neglect of the beneficial material strain hardening. The continuous strength method (CSM) is a well-established design approach, taking due account of material strain hardening in the determination of cross-section resistances, and has been recently extended to cover the design of mono-symmetric and asymmetric stainless steel open sections in compression and bending about an axis that is not one of symmetry. The CSM was assessed against the experimental and numerical results on hot-rolled austenitic stainless steel equal-leg angle section stub columns and laterally restrained beams, and shown to result in substantially more precise and consistent cross-section capacity predictions than the European code.

3D printed microstructured Au/TiO2 catalyst for hydrogen photoproduction

We successfully 3D printed Au/TiO2 monoliths for photogenerating hydrogen from water/ethanol gaseous mixtures under dynamic conditions. Monolith designs were printed by additive superposition of microfilaments of titania-based pastes. Factors influencing the efficiency of the photocatalytic reactions, including impregnation of gold nanoparticles (Au NPs), calcination temperature, diameter of microfilaments and monolith design, are investigated. The use of preformed Au NPs assured a constant Au particle size (ca. 4nm) for all samples, which allowed to a precise assessment of the effect of the design of 3D-printed titania monoliths on photocatalytic activity. The impregnation of preformed Au NPs before or after the 3D printing process has a strong influence on the photocatalytic efficiency. The pre-impregnated monoliths have a homogeneous Au NPs distribution throughout the microfilaments, whereas the post-impregnated ones present an asymmetric distribution of Au NPs, observing a high gold concentration at the surface and lower gold concentrations in the inner regions of the printed microfilaments. The gold concentration of the Au-loading suspension was reduced ca. 10 times in post-impregnated samples to ensure a similar amount of Au NPs anchored at the surface of the microfilaments, according to an XPS analysis of the pre- and post-impregnated samples. Although the photocatalytic performance of the pre-impregnated monoliths was improved when samples were calcined at 400°C, due to a stronger contact between the Au NPs and the microfilament supports, the post-impregnated samples with 100 times lower Au concentration (0.005wt.%) exhibited enhanced catalytic performances. Under similar geometric open section and photon absorption conditions, the photoproduction of hydrogen on a weight (or volume) basis increased strongly as the diameter of the filaments decreased, which is explained by a progressive increase of the surface-to-weight and surface-to-volume ratios. The best photoactivity was obtained with a post-impregnated titania monolith 3D printed with microfilaments with 200μm in diameter, which yielded 0.24molH2min−1gAu−1.

Design and performance of an aeroacoustic wind tunnel facility at the University of Bristol

This paper provides an overview of the design and performance of the new aeroacoustic wind tunnel facility at the University of Bristol. The purpose of the facility is to enable near- and far-field acoustic and aerodynamic studies on a variety of different aerodynamic components and to examine diverse noise control techniques. The facility comprises a large acoustic chamber, anechoic down to 160 Hz, and a temperature controlled closed-circuit wind tunnel with an open test section. The wind tunnel features two interchangeable rectangular nozzles with a partially shared contraction. Both nozzles are shown to possess a high flow quality with high flow uniformity and low turbulence intensity of 0.09% and 0.12% for the smaller and larger nozzle, respectively. The maximum attainable flow speeds are 40 m/s for the larger nozzle and 120 m/s for the smaller nozzle corresponding to Reynolds numbers of 2.7 million and 8.1 million per meter, respectively. In this paper, we will present various aerodynamic and acoustic results to characterize the performance of the facility. The background noise levels are found to be sufficiently low and the far-field noise measurements from a flat plate, a round cylinder and a NACA 0012 airfoil compare favorably to existing experimental observations.

Non-linear torsional vibration of lengthy thin-walled simply supported beam of open section resting on Winkler foundation

The aim of this paper is to study the non-linear torsional vibrations of lengthy thin-walled simply supported beam of open section resting on Winkler foundation. The governing differential equation of motion is derived. An effort has been made to obtain and solve the governing differential equation of large amplitude torsional vibrations of doubly symmetric thin-walled beams of open section with simply supported boundary. Approximate solutions are obtained for simply supported beams using the well-known Galerkin’s method. Plots specifying the effect of large amplitudes on nonlinear frequency of torsional vibrations for various non-dimensional beam constants are furnished. From the present study, we observe, that for lower values of Winkler stiffness parameter λ≤0.1, the non-linear frequency increases drastically as β increases. Also, it is noticed that as the value of Winkler stiffness parameter λ increases, the influence of β decreases. For higher values of λ≥30, the effect of β in the present range 0–0.1 on non-linear frequency seems to be negligible.

Displacement modes of a thin-walled beam model with deformable cross sections

A novel one dimensional beam model for analysis of prismatic thin-walled beams with deformable cross sections is introduced and a novel cross section mode determination procedure, which leads to the three dimensional beam displacement modes, is derived. The first order beam model for linear analysis includes: shear deformations related to both Timoshenko and Mindlin-Reissner type shear deformations, the warping effects of torsion, cross section distortion with related warping effects, as well as the Poisson effect with transverse displacements due to normal stress. The generality of the model allows it to handle open, closed and multi-cell cross sections with branched walls. The cross section analysis procedure leads to two types of beam displacement modes referred to as distortional beam modes and fundamental beam modes, with exponential and polynomial variations along the beam axis, respectively. It turns out that each of the beam deformation modes consists of a sum of one to four cross section displacement fields each with an individual axial variation. The displacement modes can facilitate the formulation of an advanced thin-walled beam element. The beam displacement modes will be illustrated for an open and a closed cross section.

Analytical Solutions for a Wellbore Subjected to a Non-isothermal Fluid Flux: Implications for Optimizing Injection Rates, Fracture Reactivation, and EGS Hydraulic Stimulation

Hydraulic stimulation in enhanced geothermal systems (EGS) involves massive injection of cold fluid into target hot geothermal reservoir through a long open hole section to trigger slip on preexisting fractures and enhance permeability. Fluid injection is typically conducted at a specified rate in a step-increasing manner until the pore pressure exceeds the minimum principal stress. During each step, the injection rate is kept constant. This paper presents analytical solutions for a wellbore subjected to cooling and a constant fluid flux on borehole wall and far field in situ stress in a thermoporoelastic medium with applications to hydraulic stimulations in EGS. The temporal-spatial distribution of temperature, pore pressure and stress are obtained by means of Laplace transform and load decomposition. The results show that for granite and a typical fluid injection scenario, thermal effect is pronounced in the vicinity of the wellbore. At early time, cooling-induced pore pressure/hoop stress counteract the injection induced pore pressure/hoop stress. With increasing time, the induced pore pressure and hoop stress result predominantly from fluid injection, and cooling plays a marginal role.

Structural Analysis of High-rise Buildings under Horizontal Loads: A Study on the Piedmont Region Headquarters Tower in Turin

Background:When a high-rise building is designed, the main aim is to limit transversal displacements. In addition, when vertical bracings, made up of thin open sections, are subjected to external torsion, warping and secondary torsional moment stresses arise which need to be evaluated using Vlasov’s Theory.Objective:This work analyzes the Piedmont Region Headquarters Tower, using an analytical formulation which enables the calculation of structural displacements and stresses.Methods:The analytical formulation used in the static and dynamic analysis of the structure was implemented using Matlab computation code. A computational model was also created using a commercial Finite Element Code to validate the results.Results:The results obtained with the analytical model were compared with those obtained with the FEM model. The transversal displacements, bending, torsional, and axial stresses in the vertical bracings were calculated, along with the principal natural frequencies of the structure.Conclusion:It has been proved that analytical calculation codes are a good tool for the preliminary design of a high-rise building. In particular, the proposed formulation, which has only three degrees of freedom per floor, provided results similar to those obtained using a FEM model. The great advantage of this analytical code is to speed up the computation time, which is proportional to the square of the degrees of freedom. In a FEM model, these have orders of magnitude greater than in the analytical model. Moreover, the proposed formulation allows the load distribution between the structural elements to be determined.

Effect of Wind Tunnel Blockage on the Performance of a Horizontal Axis Wind Turbine with Different Blade Number

Blockage corrections for the experimental results obtained for a small-scale wind turbine in a wind tunnel are required in order to estimate how the same turbine would perform in real conditions. The tunnel blockage is defined as the ratio of the wind turbine swept area to the wind tunnel cross-section area. Experimental measurements of the power coefficient were performed on a horizontal-axis wind turbine with two rotors of diameter equal to 2 m and different numbers of blades, namely three and five. Measurements were carried out for different tip speed ratios in the closed circuit open test section wind tunnel of the University of Perugia (Italy). The obtained experimental results were compared with the numerical ones carried out in free conditions by using a CFD approach based on the steady-RANS method with the SST k-ω turbulence model, adopting the multiple reference frame (MRF) strategy to reduce the computational effort. The comparison showed that the maximum value of blockage, which is reached in the asymptotic limit at very large tip speed ratio (TSR) values, does not depend appreciably on the number of blades. A higher number of blades, however, makes the occurrence of the maximum blockage come earlier at lower TSRs.