Abstract: Glass Fiber Reinforced Polymer (GFRP) is a major evolution for energy dissipation when used as infill material for seismic retrofitting of steel frame, a basic PMC infill wall system consists of two GFRP laminates surrounding an infill of foam core. This paper presents numerical analysis in terms of buckling resistance of GFRP sandwich infill panels system under the influence of environment temperature and stacking sequence of laminate skin. Mode of failure under in-plane compression is studied by means of numerical analysis with ABAQUS platform. Parameters considered in this study are contact length between infill and frame, laminate stacking sequence of GFRP skin and variation of mechanical properties due to increment of temperature. The analysis is done with four cases of simple stacking sequence over a range of temperature. The result showed that both the effect of temperature and stacking sequence alter the performance of entire panel system. The rises of temperature resulted in the decrements of the panel’s strength. This is due to the polymeric nature of this material. Additionally, the contact length also displays the effect on the performance of infill panel. Furthermore, the laminate stiffness can be modified by orientation of laminate, which can increase the infill panel strength. Hence, optimal performance of the entire panel system can be obtained by comparing different cases of stacking sequence.
Abstract: According to current seismic codes the structures are calculated using the capacity design procedure based on the concept of shear at the base depending on several parameters including behavior factor which is considered to be the most important parameter. The behavior factor allows designing the structure when it is at its ultimate limit state taking into account its energy dissipation through its plastic deformation. The aim of the present study is to assess the basic parameters on which is composed the behavior factor among them the reduction factor due to ductility, and those due to redundancy and the overstrength for steel moment-resisting frames of different heights and regular configuration. Analyses are conducted on these frames using the nonlinear static method where the effect of some parameters on the behavior factor, such as the number of stories and the number of spans, are taken into account. The results show that the behavior factor is rather sensitive to the variation of the number of stories and bays.
Abstract: The stability of structures made of light-gauge steel depends highly on the contribution of Shear Wall Panel (SWP) systems under horizontal forces due to wind or earthquake loads. Steel plate sheathing is often used with these panels made of cold formed steel (CFS) to improve its shear strength. In order to predict the shear strength resistance, two methods are presented in this paper. In the first method, the steel plate sheathing is modeled with plats strip taking into account only the tension and compression force due to the horizontal load, where both track and stud are modeled according to the geometrical and mechanical characteristics of the specimen used in the experiments. The theoretical background and empirical formulations of this method are presented in this paper. However, the second method is based on a micro modeling of the cold formed steel Shear Wall Panel “CFS-SWP” using Abaqus software. A nonlinear analysis was carried out with an in-plan monotonic load. Finally, the comparison between these two methods shows that the micro modeling with Abaqus gives better prediction of shear resistance of SWP than strips method. However, the latter is easier and less time consuming than the micro modeling method.
Abstract: In order to understand the seismic behavior of steel frame structure with infill FRP composite panel, simple models for simulation on the steel frame with the panel systems were developed in this study. To achieve the simple design method of the steel framed structure with the damping panel system, 2-D finite element analysis with the springs and dashpots models was conducted in ABAQUS. Under various applied spring stiffness and dashpot coefficient, the expected hysteretic energy responses of the steel frame with damping panel systems we investigated. Using the proposed simple design method which decides the stiffness and the damping, it is possible to decide the FRP and damping materials on a steel frame system.
Abstract: In this paper, we present the results of a study of TiN thin films which are deposited by a Physical Vapour Deposition (PVD) and Ion Beam Assisted Deposition (IBAD). In the present investigation the subsequent ion implantation was provided with N5+ ions. The ion implantation was applied to enhance the mechanical properties of surface. The thin film deposition process exerts a number of effects such as crystallographic orientation, morphology, topography, densification of the films. A variety of analytic techniques were used for characterization, such as scratch test, calo test, Scanning electron microscopy (SEM), Atomic Force Microscope (AFM), X-ray diffraction (XRD) and Energy Dispersive X-ray analysis (EDAX).
Abstract: Proper selection of welding parameters for getting
excellent weld is a challenge. HAZ simulation helps in identifying
suitable welding parameters like heating rate, cooling rate, peak
temperature, and energy input. In this study, the influence of weld
thermal cycle of heat affected zone (HAZ) is simulated for
Submerged Arc Welding (SAW) using Gleeble ® 3800 thermomechanical
simulator. A (Micro-alloyed) MA steel plate of thickness
18 mm having yield strength 450MPa is used for making test
specimens. Determination of the mechanical properties of weld
simulated specimens including Charpy V-notch toughness and
hardness is performed. Peak temperatures of 1300°C, 1150°C,
1000°C, 900°C, 800°C, heat energy input of 22KJ/cm and preheat
temperatures of 30°C have been used with Rykalin-3D simulation
model. It is found that the impact toughness (75J) is the best for the
simulated HAZ specimen at the peak temperature 900ºC. For parent
steel, impact toughness value is 26.8J at -50°C in transverse
direction.
Abstract: Ultrasonic pulse velocity (UPV) method has been shown for some time to provide a reliable means of estimating properties and offers a unique opportunity for direct, quick and safe control of building damaged by earthquake, fatigue, conflagration and catastrophic scenarios. On this investigation hybrid reinforced concrete has been investigated by UPV method. Hooked end steel fiber of length 50 and 30 mm was added to concrete in different proportion 0, 0.25, 0.5, and 1 % by the volume of concrete. On the other hand, polypropylene fiber of length 12, 6, 3 mm was added to concrete of 0.1, 0.2, and 0.4 % by the volume of concrete. Fifteen different mixture has been prepared to investigate the relation between compressive strength and UPV values and also to investigate on the effect of volume and type of fiber on UPV values.
Abstract: Modal analysis of a FGM plate containing the ceramic phase of Al2O3 and metal phase of stainless steel 304 was performed using ABAQUS, with the assumptions that the material has an elastic mechanical behavior and its Young modulus and density are varying in thickness direction. For this purpose, a subroutine was written in FOTRAN and linked with ABAQUS. First, a simulation was performed in accordance to other researcher’s model, and then after comparing the obtained results, the accuracy of the present study was verified. The obtained results for natural frequency and mode shapes indicate good performance of user-written subroutine as well as FEM model used in present study. After verification of obtained results, the effect of clamping condition and the material type (i.e. the parameter n) was investigated. In this respect, finite element analysis was carried out in fully clamped condition for different values of n. The results indicate that the natural frequency decreases with increase of n, since with increase of n, the amount of ceramic phase in FGM plate decreases, while the amount of metal phase increases, leading to decrease of the plate stiffness and hence, natural frequency, as the Young modulus of Al2O3 is equal to 380 GPa and the Young modulus of stainless steel 304 is equal to 207 GPa.
Abstract: This paper provides a tensile stress-strain (σ-ε) relationship for High-Strength Steel Fiber Reinforced Concrete (HSFRC). Load-deflection (P-δ) behavior of HSFRC beams tested under four-point flexural load were used with inverse analysis to calculate the tensile σ-ε relationship for various tested concrete grades (70 and 90MPa) containing 60 kg/m3 (0.76 %) of hook-end steel fibers. A first estimate of the tensile (σ-ε) relationship is obtained using RILEM TC 162-TDF and other methods available in literature, frequently used for determining tensile σ-ε relationship of Normal-Strength Concrete (NSC) Non-Linear Finite Element Analysis (NLFEA) package ABAQUS® is used to model the beam’s P-δ behavior. The results have shown that an element-size dependent tensile σ-ε relationship for HSFRC can be successfully generated and adopted for further analyses involving HSFRC structures.
Abstract: This paper covers application of an elitist selfadaptive
step-size search (ESASS) to optimum design of steel
skeletal structures. In the ESASS two approaches are considered for
improving the convergence accuracy as well as the computational
efficiency of the original technique namely the so called selfadaptive
step-size search (SASS). Firstly, an additional randomness
is incorporated into the sampling step of the technique to preserve
exploration capability of the algorithm during the optimization.
Moreover, an adaptive sampling scheme is introduced to improve the
quality of final solutions. Secondly, computational efficiency of the
technique is accelerated via avoiding unnecessary analyses during the
optimization process using an upper bound strategy. The numerical
results demonstrate the usefulness of the ESASS in the sizing
optimization problems of steel truss and frame structures.
Abstract: Optimisation of the physical and mechanical properties of cold rolled thin strips is achieved by controlling the rolling parameters. In this paper, the factors affecting the asymmetrical cold rolling of thin low carbon steel strip have been studied at a speed ratio of 1.1 without lubricant applied. The effect of rolling parameters on the resulting microstructure was also investigated. It was found that under dry condition, work roll shifting and work roll cross angle can improve the strip profile, and the result is more significant with an increase of work roll cross angle rather than that of work roll shifting. However, there was no obvious change in microstructure. In addition, effects of rolling parameters on strip profile and microstructure have also been discussed.
Abstract: For briquetting of metal chips are used hydraulic and
mechanical presses. The density of the briquettes in this case is about
60% - 70 % on the density of solid metal. In this work are presented
the results of experimental studies for briquetting of metal chips, by
using a new technology for impact briquetting. The used chips are by
Armco iron, steel, cast iron, copper, aluminum and brass. It has been
found that: (i) in a controlled impact the density of the briquettes can
be increases up to 30%; (ii) at the same specific impact energy Es
(J/sm3) the density of the briquettes increases with increasing of the
impact velocity; (iii), realization of the repeated impact leads to
decrease of chips density, which can be explained by distribution of
elastic waves in the briquette.
Abstract: The soil profile at site of the bridge project includes soft fine grained soil layer located between 5.0 m to 11.0 m in depth, it has high water content, low SPT no., and low bearing capacity. The clay layer induces high settlement due to surcharge application of earth embankment at ramp T1, ramp T2, and ramp T3 especially at heights from 9m right 3m. Calculated settlement for embankment heights less than 3m may be accepted regarding Saudi Code for soil and foundation. The soil and groundwater at the project site comprise high contents of sulfates and chlorides of high aggressively on concrete and steel bars, respectively. Regarding results of the study, it has been recommended to use stone column piles or new technology named PCC piles as soil improvement to improve the bearing capacity of the weak layer. The new technology is cast in-situ thin wall concrete pipe piles (PCC piles), it has economically advantageous and high workability. The technology can save time of implementation and cost of application is almost 30% of other types of piles.
Abstract: Fe-2%Mn-0.5%Si-0.2C steel was welded and corroded
at 600, 700 and 800oC for 20 h in 1 atm of N2/H2S/H2O-mixed gas in
order to characterize the high-temperature corrosion behavior of the
welded joint. Corrosion proceeded fast and almost linearly. It
increased with an increase in the corrosion temperature. H2S formed
FeS owing to sulfur released from H2S. The scales were fragile and
nonadherent.
Abstract: In this study, thermal fatigue properties of 400 series
ferritic stainless steels have been evaluated in the temperature ranges
of 200-800oC and 200-900oC. Systematic methods for control of
temperatures within the predetermined range and measurement of load
applied to specimens as a function of temperature during thermal
cycles have been established. Thermal fatigue tests were conducted
under fully constrained condition, where both ends of specimens were
completely fixed. It has been revealed that load relaxation behavior at
the temperatures of thermal cycle was closely related with the thermal
fatigue property. Thermal fatigue resistance of 430J1L stainless steel
is found to be superior to the other steels.
Abstract: This paper investigates the application of metallic
coatings on high fiber volume fraction carbon/epoxy polymer matrix
composites. For the grip of the metallic layer, a method of modifying
the surface of the composite by introducing a mixture of copper and
steel powder (filler powders) which can reduce the impact of thermal
spray particles. The powder was introduced to the surface at the time
of the forming. Arc spray was used to project the zinc coating layer.
The substrate was grit blasted to avoid poor adherence. The porosity, microstructure, and morphology of layers are
characterized by optical microscopy, SEM and image analysis. The
samples were studied also in terms of hardness and erosion resistance.
This investigation did not reveal any visible evidence damage to the
substrates. The hardness of zinc layer was about 25.94 MPa and the
porosity was around (∼6.70%). The erosion test showed that the zinc
coating improves the resistance to erosion. Based on the results
obtained, we can conclude that thermal spraying allows the production
of protective coating on PMC. Zinc coating has been identified as a
compatible material with the substrate. The filler powders layer
protects the substrate from the impact of hot particles and allows
avoiding the rupture of brittle carbon fibers.
Abstract: A 15-storey RC building, studied in this paper, is
representative of modern building type constructed in Madina City in
Saudi Arabia before 10 years ago. These buildings are almost
consisting of reinforced concrete skeleton i.e. columns, beams and
flat slab as well as shear walls in the stairs and elevator areas
arranged in the way to have a resistance system for lateral loads
(wind – earthquake loads). In this study, the dynamic properties of
the 15-storey RC building were identified using ambient motions
recorded at several, spatially-distributed locations within each
building. Three dimensional pushover analysis (Nonlinear static
analysis) was carried out using SAP2000 software incorporating
inelastic material properties for concrete, infill and steel. The effect
of modeling the building with and without infill walls, on the
performance point as well as capacity and demand spectra due to EQ
design spectrum function in Madina area has been investigated. ATC-
40 capacity and demand spectra are utilized to get the modification
factor (R) for the studied building. The purpose of this analysis is to
evaluate the expected performance of structural systems by
estimating, strength and deformation demands in design, and
comparing these demands to available capacities at the performance
levels of interest. The results are summarized and discussed.
Abstract: One of the main purposes of designing bucklingrestrained
braces is the fact that the entire lateral load is wasted by
the braces, the entire gravitational load is moved to the foundation
through the beams, and the columns can be moved to the foundation.
In other words, braces are designed for bearing lateral load. In the
implementation of the structure, it should be noted that the
implementation of various parts of the structure must be conducted in
such a way that the buckling-restrained braces would not bear the
gravitational load. Moreover, this type of brace has been investigated
under impact loading, and the design goals of designing method
(direct motion) are controlled under impact loading. The results of
dynamic analysis are shown as the relocation charts of the floors and
switch between the floors. Finally, the results are compared with each
other.
Abstract: Hard coatings are widely used in cutting and forming
tool industries. Titanium Nitride (TiN) possesses good hardness,
strength, and corrosion resistance. The coating properties are
influenced by many process parameters. The coatings were deposited
on steel substrate by changing the process parameters such as
substrate temperature, nitrogen flow rate and target power in a D.C
planer magnetron sputtering. The structure of coatings were analysed
using XRD. The hardness of coatings was found using Micro
hardness tester. From the experimental data, a regression model was
developed and the optimum response was determined using Response
Surface Methodology (RSM).
Abstract: In the present work, forming limit diagrams and strain
distribution profile diagrams for extra deep drawing steel at room and
elevated temperatures have been determined experimentally by
conducting stretch forming experiments by using designed and
fabricated warm stretchforming tooling setup. With the help of
forming Limit Diagrams (FLDs) and strain, distribution profile
diagrams the formability of Extra Deep Drawing steel has been
analyzed and co-related with mechanical properties like strain
hardening COEFFICIENT (n) and normal anisotropy (r−). Mechanical
properties of EDD steel from room temperature to 4500C were
determined and discussed the impact of temperature on the properties
like work hardening exponent (n) anisotropy (r-) and strength
coefficient of the material. In addition, the fractured surfaces after
stretching have undergone the some metallurgical investigations and
attempt has been made to co-relate with the formability of EDD steel
sheets. They are co-related and good agreement with FLDs at various
temperatures.