Journal of Materials and Engineering Structures
Not a member yet
316 research outputs found
Sort by
Analysis, Behavior, Strengthening and repairing of Reinforced Concrete Corbels: Comprehensive Review
Full text linkIn this review, an extensive survey on the theoretical models and approaches that were proposed in literature to study the behavior of RC corbels has been presented. Such approaches included the shear friction approach, strut and tie model, finite element and Neural networks. Moreover, the review has been extended to consider the studies conducted experimentally by researchers and scholars to investigate the response of the RC corbels. Furthermore, various proposals that were suggested regarding strengthening and repairing of RC corbels have been discussed. Different materials have been used to improve the performance of RC corbels, such as steel fibers, FRP composites, NSM steel bars, NSM CFRP bars and composite sections have been considered. The most important findings reported in the relevant literature have been summarized. In addition, several recommendations to extend the studies concerning the RC corbel to improve the knowledge about the behavior of this significant structural member have been presented
Modulus and stiffness of laterally loaded single free headed pile in stratified soil
Full text linkLaterally loaded piles gained its attention when structures like transform towers, offshore structures etc., met huge horizontal loads. Initially, to study the behaviour of laterally loaded piles, homogeneous soil is assumed; whereas in reality the soil stratum would be stratified/ multi-layer soil with various consistency and relative density. Considering this real field situation, an 1g experimental investigation is carried out on a single pile embedded in layered soil by varying the number of layers with respect to the length of the pile. With a sand layer on top and in-between, it increases the lateral capacity of the pile. The main soil-structure interaction parameters are modulus and stiffness factor, the modulus of the homogenous sand layer is very high when compared to the clay layer sandwiched between the sand layer
Studies on hardness and tensile testing of AlSi10Mg produced by selective laser melting
Full text linkAlSi alloys have a wide range of applications in the Additive Manufacturing area, including automotive, aerospace, and residential industries. Despite their appealing mix of mechanical qualities, high heat conductivity, and low weight, they are more difficult to treat by Selective Laser Melting due to their high reflectivity and heat conductivity. In this work, samples were exposed to heat treatment at temperatures of 400°C, 500°C, and 550°C and an artificial ageing treatment for 180°C for 12h, to control the mechanical behaviour of selective-laser- melting (SLM)-produced AlSi10Mg alloys, after which material properties such as tensile strength and hardness were evaluated. The highest tensile and yield strengths are shown by the as-built SLM specimens, which have values of 432.45 and 322.76 MPa. On the other hand, the lowest tensile and yield strengths are shown by the solution heat-treated specimens, which have values of 168.11 and 90.52 MPa. Similar to as-built SLM specimens, the highest hardness value measured was 132.55Hv1.
Determination of the dynamic response due to the collision of adjacent structures as a function of the variation of the shear wave velocity
Full text linkThis article studies the coupled effect of the collision of adjacent buildings and the soil-structure interaction on the dynamic responses in terms of displacement and impact force. To illustrate the proposed procedure, an example of two 8-storey reinforced concrete buildings subjected to the 1941 el Centro earthquake was considered. The procedure consists in solving the dynamic equation of motion by Newmark's method using a program under matlab. The parameters of the soil-structure interaction are introduced by the impedance equations in the equation of motion. The analysis of the results obtained revealed that even if the two structures have identical characteristics, the variation of the shear wave speed completely changes their response in displacement and in impact force which can distort the dimensioning of the seismic joints
Assessment of Influence of Reinforcement Detailing on Blast Resistance of Reinforced Concrete Beam-column Connections
Full text linkThis study investigates the influence of blast loading on Reinforced Concrete (RC) beam-column connections, which are critical components for maintaining the structural integrity of buildings during extreme events like explosions. The impact of varying blast loads, detonation distance, and reinforcement detailing on the extent of damage in the RC frame and connections is analyzed using ABAQUS/CAE Finite Element Method (FEM) software. Joint rotation is used as a damage indicator to assess the damage level in the structure. The study evaluates the effect of reinforcement detailing on the blast damage resistance of the RC frame and connections and proposes recommendations for reducing damage in the connections through the effective placement of steel reinforcement. The effectiveness of different configurations of reinforcing steel bars is also analyzed, and the presence of shear and diagonal reinforcements is found to reduce joint damage by 3-4 times. This study highlights the significance of reinforcement detailing and recommends its careful consideration in the design of blast-resistant structures
The Energy Performance of Shading Element and Double Skin Facade System Integration into Office Buildings in Turkey
Full text linkEnergy efficiency in building design tends to be important in reducing the share of construction sector in energy consumption and environmental problems caused by it. In this study, energy performance of an existing office structure was evaluated by integrating shading elements and double skin facade systems within the scope of energy efficiency in buildings. Initially, current energy performance of the building was examined by design builder program and then, the shading element alternatives and the double skin facade system alternatives were separately integrated into the structure and simulated by solar tool and design builder program. Alternatives with the highest energy performances were determined in both building components. Later in the study, the shading element and the double skin facade system alternatives, which gave the most successful results, were integrated into the building model simultaneously and the energy performance thus evaluated was compared with the energy performance of the existing building. According to results, the Shaded Double Skin Facade scenario indicated a drop in heating load of around 2% and a decrease in cooling load of about 45% compared to the present building model
Coefficient of surface water absorption: A non-destructive test index for evaluation and quality grading of cover-concrete
Full text linkSurface Water Absorption Test (SWAT) has long been proposed as a non-destructive testing device for evaluation and grading of the quality of the cover concrete and standardization of SWAT is still in process. In this study, the acceptability and validity of a new water sorptivity index of the SWAT method - the coefficient of surface water absorption (CSWA), are appraised by a correlative assessment between CSWA and the coefficient of air permeability (kT values) measured by the Torrent’s double chamber air permeability device. The tests were conducted on fourteen different kinds of concrete at different ages, produced with three different cement types, four water-to-binder ratios, and four curing conditions. The results revealed a good correlation between CSWA and kT for both the specimens with uniform moisture content and the ones with varying degrees of moisture gradients. The findings validate the CSWA as an effective quality control index during design as well as a durability quantifier for evaluating the water absorption resistance of in-situ concrete structures
Performance of sustainable lightweight foam concrete with synthetic micro and macro fibers as reinforcement
Full text linkIn the current research, lightweight foam concrete blocks made from recycled concrete powder, reinforced with plastic macro fibers and polypropylene micro fibers have been proposed as sustainable concrete approach. By adding Recycled Concrete Powder (RCP) in the amount ranging from 15 to 30% by weight of cement, have only a mild impact on the strength properties of foam concrete. Addition of mono fibers and hybrid fibers improves the mechanical properties of foam concrete with RCP. The tensile strength, flexural strength and compressive strengths of concrete are enhanced by the addition of micro and macro fibres. As the percentage of macro fiber increases the strength of the light weight concrete also increases. when the proportion of micro fibers is more compared to macro fibers, the strength properties are slightly reducing as the micro fibers reduces the plasticity of foam mix. In hybrid fiber reinforcement 0.3% plastic and 0.2% polypropylene showed an improvement in mechanical properties compared to other specimens.
Efficient prediction of axial load-bearing capacity of concrete columns reinforced with FRP bars using GBRT model
Full text linkThe behavior of concrete columns reinforced with fiber reinforced polymer (FRP) bars is different from conventional reinforced concrete columns due to the mechanical properties of FRP bars. This study develops a novel machine learning (ML) model, namely gradient boosting regression tree (GBRT), for efficiently predicting the axial load-bearing capacity (ALC) of concrete columns reinforced with FRP bars. A data base containing 283 experimental results is collected to develop the ML model. Seven code-based and empirical-based equations are also included in comparison with the developed ML models. Moreover, we also propose a multiple linear regression (MLR)-based formula for calculating the ALC of the FRP-concrete column. The performance results of GBRT model are compared with those of published formulas and the proposed MLR-based formula. Statistical properties including , , and are calculated to evaluate the accuracy of those predictive models. The comparisons demonstrate that GBRT outperforms other models with very high values and small . Moreover, the influence of input parameters on the predicted ALC isevaluated. Finally, an efficient graphical user interface tool is developed to simplify the practical design process of FRP-concrete columns
Free Vibration of Statically Deformed Bi-directionally Graded Timoshenko Beam on Elastic Foundation
Full text linkIn the present work, geometric nonlinearity is taken into consideration to study the free vibration response of nonlinearly deflected Timoshenko beam with bi-directional gradation, resting on an elastic foundation of Winkler type. Exponential variation of material properties is considered along the thickness and length direction. In order to carry out the present numerical study, the entire physical domain of analysis is converted into a normalized domain and suitable number of computational points are created on it to conduct a whole domain analysis. The adopted mathematical formulation is displacement based and semi-analytical. A unique methodology is used for the formulation, in which the static analysis is taken first under large amplitude static force, then a subsequent eigenvalue analysis is performed on the known statically deformed beam profile. Appropriate energy principles are utilized for both analyses to derive the equation of motion in matrix form, which are solved with the help of the algorithm of direct substitution method. Generated results are validated with the results of previously published paper. New sets of result are also presented as benchmark results to represent the impact of bi-directional gradation and elastic foundation on nonlinear vibration response