• Structural Engineering and Mechanics
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• v.42 no.4
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• pp.571-587
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• 2012

This paper presents results of a numerical analysis performed on a corrugated steel plate (CSP) bridge during a backfilling process. The analysed bridge structure was a box culvert having a span of 12315 mm as well as a clear height of 3550 mm. Obtained calculation results were compared with the experimental ones. The paper is presented with the application of the Fast Lagrangian Analysis of Continua (FLAC) program based on the finite differences method (FDM) to determine behaviour of the soil-steel bridge structure during backfilling. The assumptions of a computational 2D model of soil-steel structure with a non-linear interface layer are described. Parametric analysis of the interface element is also given in order to receive the most realistic calculation results. The method based on this computational model may be used with large success to design calculations of this specific type of structure instead of the conventional and fairly inaccurate analytical methods. The conclusions drawn from such analysis can be helpful mostly for the assessment of the behaviour of steel-soil bridge structures under loads of backfilling. In consideration of an even more frequent application of this type of structure, conclusions from the conducted analysis can be generalized to a whole class of similar structural bridge solutions.

• The KSFM Journal of Fluid Machinery
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• v.12 no.2
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• pp.39-45
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• 2009

Leakage flow through turbine blade tip gap causes strong leakage vortex near the blade suction side and induces large aerodynamic losses. In this study, the conventional plane tip and various squealer tip blades were tested in a linear cascade in order to measure the effect of the tip shape on the total pressure loss. Three tip gap clearances of 0.6%, 1.3%, and 2.0% of blade span were tested. Flow measurement was conducted at one chord downstream from the trailing edge with a five-hole probe. Results showed that the leakage vortex was stronger than passage vortex and the mass averaged overall total pressure loss through the cascade was the lowest for suction side blade tip case. For all tested cases, the area averaged overall total pressure loss was increased as the tip clearance increased.

• Journal of the Korea Furniture Society
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• v.22 no.4
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• pp.323-329
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• 2011

In our country, domestic species can not be used as a structural member because we have not yet grading system. So, to utilize as a basic data of grading system, bending test and numerical modelling on structural member were conducted in this study. 35 of Douglas-fir, 2" ${\times}$ 6", span 2.4 m were tested for the bending properties, and Ansys software was used to analyze the numerical modelling on the structural members. The data of knots were inspected and applied in numerical modelling. To obtain the accuracy of analysis, nonlinear numerical analysis was carried out instead of linear numerical analysis. Ultimate load had a wide range from 4883N to 11,738 N, and maximum deformation also had a range from 26 mm to 68 mm. Average of ultimate load was 8,616 N, and that of maximum deformation was 48 mm. The distinctive features of failure types were simple tension type and cross-grain tension type. Ulitmate load and maximum deformation from numerical modelling were 7,504 N and 37 mm. The numerical modelling drawn by this study is available to all species, and reasonable prediction on the bending performance is possible with only some material properties.

• Advances in materials Research
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• v.9 no.2
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• pp.133-153
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• 2020

In this paper, an improved theoretical interfacial stress and slip analysis is presented for simply supported composite steel-concrete beam bonded with an adhesive. The adherend shear deformations have been included in the present theoretical analyses by assuming a linear shear stress through the thickness of the adherends, while all existing solutions neglect this effect. Remarkable effect of shear deformations of elements has been noted in the results. It is observed that large shear is concentrated and slip at the edges of the composite steel-concrete. Comparing with some experimental results from references, analytical advantage of this improvement is possible to determine the normal and shear stress to estimate exact prediction of normal and shear stress interfacial along span between concrete and steel beam. The exact prediction of these stresses will be very important to make an accurate analysis of the mode of fracture. It is shown that both the normal and shear stresses at the interface are influenced by the material and geometry parameters of the composite steel-concrete beam. This research is helpful for the understanding on mechanical behavior of the connection and design of such structures.

• Structural Engineering and Mechanics
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• v.6 no.3
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• pp.259-274
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• 1998

The test results from non-destructive and destructive field testing of a three-span deteriorated reinforced concrete slab bridge are used as a vehicle to examine the reliability of available tools for finite-element analysis of in-situ structures. Issues related to geometric modeling of members and connections, material models, and failure criteria are discussed. The results indicate that current material models and failure criteria are adequate, although lack of inelastic out-of-plane shear response in most nonlinear shell elements is a major shortcoming that needs to be resolved. With proper geometric modeling, it is possible to adequately correlate the measured global, regional, and local responses at all limit states. However, modeling of less understood mechanisms, such as slab-abutment connections, may need to be finalized through a system identification technique. In absence of the experimental data necessary for this purpose, upper and lower bounds of only global responses can be computed reliably. The studies reaffirm that success of finite-element models has to be assessed collectively with reference to all responses and not just a few global measurements.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.918-927
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• 2008

The problems associated with constructing high-speed concrete track embankments over soft compressible soil has lead to the development and/or extensive use of many of the ground improvement techniques used today. Drains, surcharge loading, and geosynthetic reinforcement, have all been used to solve the settlement and embankment stability issues associated with construction on soft soils. Geosynthetic-reinforced embankment supporting piles method consist of vertical columns that are designed to transfer the load of the embankment through the soft compressible soil layer to a firm foundation and one or more layers of geosynthetic reinforcement placed between the top of the columns and the bottom of the embankment. In the paper, the evaluations of a seismic performance of geosynthetic-reinforced embankment piles for a ultra soft ground during earthquake were studied. the equivalent linear analysis was performed by SHAKE for soft ground. A seismic performance analysis of Piles was performed by GROUP PILE and PLAXIS for geosynthetic-reinforced embankment piles. Guidelines is required for pile displacement during earthquake. Conclusions of the studies come up with a idea for soil stiffness, conditions of pile cap, pile length and span.

• Computers and Concrete
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• v.21 no.6
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• pp.607-622
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• 2018

A non-linear finite element model (FEM) was constructed using a three-dimensional software (ATENA-3D) to investigate the effect of strengthening on the behavior of prestressed hollow-core (PHC) slabs with or without openings. The slabs were strengthened using near surface mounted (NSM)-carbon fiber reinforced polymer (CFRP) strips. The constructed model was validated against experimental results that were previously reported by the authors. The validated FEM was then used to conduct an extensive parametric study to examine the influence of prestressing reinforcement ratio, compressive strength of concrete and strengthening reinforcement ratio on the behavior of such slabs. The FEM results showed good agreement with the experimental results where it captured the cracking, yielding, and ultimate loads as well as the mid-span deflection with a reasonable accuracy. Also, an overall enhancement in the structural performance of these slabs was achieved with an increase in prestressing reinforcement ratio, compressive strength of concrete, external reinforcement ratio. The presence of openings with different dimensions along the flexural or shear spans reduced significantly the capacity of the PHC slabs. However, strengthening these slabs with 2 and 4 (64 and $128mm^2$ that represent reinforcement ratios of 0.046 and 0.092%) CFRP strips was successful in restoring the original strength of the slab and enhancing post-cracking stiffness and load carrying capacity.

• Computers and Concrete
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• v.24 no.1
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• pp.37-49
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• 2019

In this study, the shear behaviour of reinforced concrete (RC) beams that were retrofitted using precast panels of ultra-high performance fiber reinforced concrete (UHPFRC) is presented. The precast UHPFRC panels were glued to the side surfaces of RC beams using epoxy adhesive in two different configurations: (i) retrofitting two sides, and (ii) retrofitting three sides. Experimental tests on the adhesive bond were conducted to estimate the bond capacity between the UHPFRC and normal concrete. All the specimens were tested in shear under varying levels of shear span-to-depth ratio (a/d=1.0; 1.5). For both types of configuration, the retrofitted specimens exhibited a significant improvement in terms of stiffness, load carrying capacity and failure mode. In addition, the UHPFRC retrofitting panels glued in three-sides shifted the failure from brittle shear to a more ductile flexural failure with enhancing the shear capacity up to 70%. This was more noticeable in beams that were tested with a/d=1.5. An approach for the approximation of the failure capacity of the retrofitted RC beams was evolved using a multi-level regression of the data obtained from the experimental work. The predicted values of strength have been validated by comparing them with the available test data. In addition, a 3-D finite element model (FEM) was developed to estimate the failure load and overall behaviour of the retrofitted beams. The FEM of the retrofitted beams was conducted using the non-linear finite element software ABAQUS.

• Structural Engineering and Mechanics
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• v.69 no.2
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• pp.155-162
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• 2019

It is very common to find an empirical formulation in an earthquake design code to calculate fundamental vibration period of a structural system. Fundamental vibration period or frequency is a key parameter to provide adequate information pertinent to dynamic characteristics and performance assessment of a structure. This parameter enables to assess seismic demand of a structure. It is possible to find an empirical formulation related to reinforced concrete structures, masonry towers and slender masonry structures. Calculated natural vibration frequencies suggested by empirical formulation in the literatures has not suits in a high accuracy to the case of rest of the historical masonry bridges due to different construction techniques and wide variety of material properties. For the listed reasons, estimation of fundamental frequency gets harder. This paper aims to present an empirical formulation through Mean Square Error study to find ambient vibration frequency of historical masonry bridges by using a non-linear regression model. For this purpose, a series of data collected from literature especially focused on the finite element models of historical masonry bridges modelled in a full scale to get first global natural frequency, unit weight and elasticity modulus of used dominant material based on homogenization approach, length, height and width of the masonry bridge and main span length were considered to predict natural vibration frequency. An empirical formulation is proposed with 81% accuracy. Also, this study draw attention that this accuracy decreases to 35%, if the modulus of elasticity and unit weight are ignored.

• Advances in aircraft and spacecraft science
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• v.9 no.5
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• pp.377-400
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• 2022

The aim of this work is a numerical comparison (FEM) between lattice pyramidal-core panel and honeycomb core panel for different core thicknesses. By evaluating the mid-span deflection, the shear rigidity and the shear modulus for both core types and different core thicknesses, it is possible to define which core type has got the best mechanical behaviour for each thickness and the evolution of that behaviour as far as the thickness increases. Since a specific base geometry has been used for the lattice pyramidal core, the comparison gives us the opportunity to investigate the unit cell strut angle giving the higher mechanical properties. The presented work considers a detailed FEM modelling of a standard 3-point bending test (ASTM C393/C393M Standard Practice). Detailed FEM modelling addresses to detailed discretization of cores by means of beam elements for lattice core and shell elements for honeycomb core. Facings, instead, have been modelled by using shell elements for both sandwich panels. On lattice core structure, elements of core and facings are directly connected, to better simulate the additive manufacturing process. Otherwise, an MPC-based constraint between facings and core has been used for honeycomb core structure. Both sandwich panels are entirely built of Aluminium alloy. Prior to compare the two models, the FEM sandwich panel model with lattice pyramidal core needs to be validated with 3-point bending test experimental results, in order to ensure a good reliability of the FEM approach and of the comparison. Furthermore, the analytical validation has been performed according to Allen's theory. The FEM analysis is linear static with an increasing midspan load ranging from 50N up to 500N.