Artificial neural network and regressed beam-column connection explicit mathematical moment-rotation expressions

Steel flush endplate beam-column connections behavior is commonly described by the moment-rotation, M-φ, relationship, which is characterized by two essential terms; resistant moment, Mj, Rd, and initial rotational stiffness, Sj, init. A great amount of concerted effort has been invested worldwide to either experimentally or analytically describe these properties due to geometrical and material variations. However, these methods are either costly, laborious, or time-consuming. Therefore, acknowledging the wealth of literature information, this paper formulates a set of practically convenient mathematical M-φ expressions by means of artificial neural network (ANN) and multi-linear regression (MLR) approaches utilizing the MATLAB software. Differing from most existing machine learning variants, the paper offers explicit expressions for maximum moment, Mmax, and Sj, init, which can be characterized through a simplistic insertion of input parameters in terms of beam depth, beam width, thickness of beam flange, thickness of beam web, column depth, column width, endplate depth, endplate thickness, and bolt capacity. The computed Mmax and Sj, init can then be adopted to express the currently defined continuous M-φ relationship. By statistical evaluation, it is witnessed that the mean-absolute-percentage error (MAPE) and correlation coefficient (R2) of both ANN and MLR methods are of remarkable prediction vitality. Also, ANN outperforms slightly MLR model in the prediction of both Mmax and Sj, init although both approaches agree closely with the source data. Therefore, both approaches are of high reliability in predicting Mmax and Sj, init as well as in characterizing the M-φ relationship of the flush endplate beam-column connections for further engineering analysis and design purposes

Spent ground coffee – awaking the sustainability prospects

This paper outlines the threat of spent coffee ground (SCG) towards environmental health and some promising remedial efforts carried out by the scientific community working against it. To maintain human and earth wellbeing, massive biowastes left behind by the rising popularity of coffee drinking and its processing must be properly addressed. The recent waste to wealth value engineering efforts carried out to repurpose these biowastes are first presented. Some promising applications of SCGs in various prospective civil engineering areas alongside their favorable findings are then summarized. Attributed to beneficial properties as reported in existing studies, silica fume is recommended as the potential constituent to mix with SCG for future construction materials exploration in overcoming both the biowaste and industrial waste issues

Towards sustainable polymeric materials: zero waste, green and self-healing

Although polymeric materials are widely adopted in various applications, the sustainability of the materials is often controversial, particularly on the current handling of polymeric wastes and the use of non-renewable resources as raw materials. A brief review is hence given to outline recent efforts that promote sustainable value of the materials. The discussion starts with the recycling activities of polymeric wastes. Next, the concept of ecofriendly composites, which include bio-based and biodegradable, is discussed. Then, a note on inclusion of self-healing functionality in polymeric composite that is seen as another promising methodology in meriting the sustainability of polymeric materials is offered. Furthermore, the feasibility and possible improvement of the aforementioned methodologies (i.e. zero waste and green concept) are highlighted and discussed. In conclusion, more research works on the individual or combination of the improved methodologies and a concise evaluator are needed to extend further the sustainable potential of polymeric materials

Serviceability assessment of composite footbridge under human walking and running loads

Footbridge responses under loads induced by human remain amongst the least explored matters, due to various uncertainties in determining the description of the imposed loadings. To address this gap, serviceability of an existing composite footbridge under human walking and running loadings is analyzed dynamically in this paper employing a finite element approach. The composite footbridge is made-up of a reinforced concrete slab simply supported at two ends on top of two T-section steel beams. To model the walking and running loads, a harmonic force function is applied as the vibration source at the center of the bridge. In the model verification, the computed natural frequency of footbridge exhibits a good agreement with that reported in literature. The vibration responses in terms of peak acceleration and displacement are computed, from which they are then compared with the current design standards for assessment. It is found that the maximum accelerations and displacements of composite footbridge in presence of excitations from one person walking and running satisfy the serviceability limitation recommended by the existing codes of practice. In conclusion, the studied footbridge offers sufficient human safety and comfort against vibration under investigated load prescription

Editorial scope – waste management and recycling

The present editorial scope of the Journal of Civil Engineering, Science, and Technology (JCEST) emphasizes one of the main disciplines of civil engineering: waste management and recycling. Waste management studies provide insights into new waste management techniques, such as recycling, composting, and waste-to-energy technologies, all of which are essential in reducing the volume of waste in landfills. In this brief editorial paper, information is gathered from the freely-accessible Scopus database to identify common keywords found in published papers related to waste management and recycling in the past decade. Based on the analysis, “waste” is found to be the top keyword in articles published on this topic in JCEST. The primary aim of this exercise is to provide researchers with a brief guide to explore the latest knowledge and advancements in waste management and recycling, in safeguarding the cleanliness and safety of our environment

Bending response of cross-ply laminated composite plates with diagonally perturbed localized interfacial degeneration

A laminated composite plate element with an interface description is developed using the finite element approach to investigate the bending performance of two-layer cross-ply laminated composite plates in presence of a diagonally perturbed localized interfacial degeneration between laminae. The stiffness of the laminate is expressed through the assembly of the stiffnesses of lamina sub-elements and interface element, the latter of which is formulated adopting the well-defined virtually zero-thickness concept. To account for the extent of both shear and axial weak bonding, a degeneration ratio is introduced in the interface formulation. The model has the advantage of simulating a localized weak bonding at arbitrary locations, with various degeneration areas and intensities, under the influence of numerous boundary conditions since the interfacial description is expressed discretely. Numerical results show that the bending behavior of laminate is significantly affected by the aforementioned parameters, the greatest effect of which is experienced by those with a localized total interface degeneration, representing the case of local delaminatio

Finite element modeling of laminated composite plates with locally delaminated interface subjected to impact loading

This paper investigates the effects of localized interface progressive delamination on the behavior of two-layer laminated composite plates when subjected to low velocity impact loading for various fiber orientations. By means of finite element approach, the laminae stiffnesses are constructed independently from their interface, where a well-defined virtually zero-thickness interface element is discreetly adopted for delamination simulation. The present model has the advantage of simulating a localized interfacial condition at arbitrary locations, for various degeneration areas and intensities, under the influence of numerous boundary conditions since the interfacial description is expressed discretely. In comparison, the model shows good agreement with existing results from the literature when modeled in a perfectly bonded state. It is found that as the local delamination area increases, so does the magnitude of the maximum displacement history. Also, as top and bottom fiber orientations deviation increases, both central deflection and energy absorption increase although the relative maximum displacement correspondingly decreases when in contrast to the laminates perfectly bonded state

Monotonic behaviour of beam-to-column connections with double channel cold-formed steel sections

Cold-formed steel is a lightweight construction material generally in C or Z shaped produced by cold rolling from strip steel. It can be applied in the Industrialized Building System (IBS) in order to reduce the time and cost in construction project. Partial strength connection is a connection whereby the moment resistance of the connection is less than that of the moment capacity of the connected beam. In this paper, Numerical simulation is conducted by using ANSYS Workbench 14.0 in order to predict the structural behaviors of cold formed steel partial strength connection. The objective of this study is to develop moment rotation curve for flange-web-cleat connection using double channel cold formed steel section under monotonic loading. Experiment test results are then used to compare and validate the results from the finite element modeling. This study aims to understand the behaviour of cold-formed steel connections under monotonic loading. The beam section of 1.5-meter length and column of 3-meter length is modeled in this study. Three different beam depth have been selected in this study, which is 150mm, and the depth of column section is fix to 250mm. Brackets connections were chosen and all connections were formed using bolts. The monotonic load is applied at 1000mm from the column surface. The stiffness and moment capacity is obtained from the moment rotation curve which plotted from the modeling results. As a conclusion, The FEM initial results showed good agreement with experimental results

Low-velocity impact of composite sandwich plate with facesheet indentation description

Composite sandwich structures are applied in many engineering fields due to their high strength and stiffness but lightweight properties. There are currently not many studies that simultaneously consider both indentation and strain failure in the composite sandwich plate especially in presence of impact loading. Such knowledge is necessary to determine the facesheet strain after impact in order to find out whether the facesheet is totally failed as a result of indentation deformation. Hence, the purpose of this study is to model numerically the top facesheet indentation and strain failure of a fixed-end composite sandwich plate with honeycomb core when it is subjected to low-velocity impact at the center. The faceheets are made from Hercules AW193-PW prepreg consisting of AS4 fibers in a 3501-6 matrix (carbon/epoxy) with a stacking sequence of [0/90]. The honeycomb core is made from HRH 10 1/8-3.0 Nomex honeycomb (Ciba-Geigy). Type of the impactor used in this study is flat-ended cylinder, which is made from case-hardened steel. The composite sandwich plate is modeled as a two-dimensional problem with five and three degrees of freedom per node for the facesheets and honeycomb core, respectively. Only the stiffness matrix, [K], and the mass matrix, [M], are considered in determining the responses of the plate. Responses in terms of indentation, strain failure and displacement are explored for various facesheet and core properties. It is found that an increase in number of ply and ply thickness reduce the indentation on the top facesheet. Also, the most effective parameter in improving the strain failure of the top facesheet is the crushing resistance of the core

Thermal Performance of Structural Lightweight Concrete Composites for Potential Energy Saving

Residential consumption dominates the energy expenditure of heating and cooling systems, especially in tropical climates where building envelopes play an important role in energy efficiency. The thermal properties of concrete that are commonly employed as the building envelope material affect directly human comfort in a building. In addressing both the concrete thermal performance and industrial waste issues, this paper experimentally studies the concrete compressive strength and thermal properties used later for comparative energy analysis for human comfort. Four design mixes and a conventional concrete as control specimen are considered utilizing industrial wastes; palm oil fly ash (POFA), lightweight expanded clay aggregate (LECA), oil palm shell (OPS), and quarry dust, as constituents. These mixes are cast for cube compressive strength (to ensure the achievement of structural concrete requirement) and small-scaled wall tests. The measurement of surface temperatures of scaled wall tests is conducted in a polystyrene box to determine the concrete time lag and decrement factor. It is found that the density of concrete governs the compressive strength and that air pockets in the concrete matrix play an essential role as far as the thermal properties are concerned. From the energy analysis, structural lightweight concrete may save approximately 50% of the residential energy consumptio