Civil Engineering Applications Research Articles

Strength Characteristics of Geopolymer Synthetic Sand Using Fly Ash

Sand is a naturally available resource that has numerous applications in civil engineering. Due to a rapid increase in construction activities and exploitation of natural resources, there has been a scarcity of natural river sand (NRS), causing environment related issues such as erosion of riverbanks and the lowering of the water table. Hence, there is a need to identify and process sustainable alternative granular materials such as geopolymer synthetic sand (GPSS). In this connection, an attempt has been made for the effective utilization of fly ash in the synthesis of granular materials through geopolymerization. Geopolymer synthetic sand was prepared using 12 M NaOH solution at 100°C for 1 h and the granules produced were used as an alternative for natural river sand. The granulated materials were characterized by their physical properties [specific gravity, water absorption, grain size distribution, specific surface area, and scanning electron microscope (SEM)], chemical properties [pH, electrical conductivity (EC), total dissolved solids (TDS), and cation exchange capacity (CEC)], engineering properties (cohesion, angle of shearing resistance, optimum moisture content and maximum dry density, and hydraulic conductivity), mineralogical properties [X-ray diffraction (XRD)], and thermal properties [thermogravimetric analysis (TGA) and differential thermal analysis (DTA)]. In addition, compressive strength tests were performed on GPSS and NRS mortar. It was noted that GPSS mortar attained similar strength as NRS mortar. Based on the experimental investigations and microanalysis, it can be concluded that GPSS granules have the potential for use as an alternative to natural river sand.

Effect of Fire on Concrete Contribution to ShearResistance of GFRP RC Beams

The use of fiber-reinforced polymer (FRP) bars is becoming commonplace in various civil engineering applications due to the several advantages they offer over traditional materials. However, limited knowledge about some aspects of the behavior of FRP bars, particularly when subjected to severe fires, is hampering their widespread use. This paper presents the results of a research program to investigate the shear behavior of glass-FRP (GFRP)-reinforced beams exposed to severe fires. Three reinforced concrete (RC) beam specimens with a cross-sectional width and height of 150 mm and 300 mm, respectively, and with a total length of 1700 mm were constructed and tested under four-point bending load up to failure. The main test variables were the reinforcement ratio and the fire. The experimental results show that all beams failed as a result of diagonal tension cracking. The shear resistance and stiffness of the RC beams decreased when the beams are exposed to fire at the same reinforcement ratio. Keywords: GFRP bars, reinforced concrete beams, fire, shear capacity, crack patterns, modes of failure.

Valorization of a Steel Industrial Co-Product for the Development of Alkali-Activated Materials: Effect of Curing Environments

Abstract While natural resources are becoming scarce and climate change is accelerating, the recovery and recycling of wastes and by-products is an effective way to deal with the economic and ecological constraints of recent decades. The valorization of industrial by-products in civil engineering is a common practice either by their incorporation during the manufacture of Portland cements or as a partial replacement of cement during the production of concrete. The present work aims to develop waste-based alkali-activated materials WAAMs intended for civil engineering applications as a potential alternative to cement-based materials. A steel industrial by-product called commonly granulated blast furnace slag GBFS was used alone as a solid CaO-rich precursor; two alkaline activators such us sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) were used separately for the production of two-part alkali-activated materials. Besides the microstructure analysis of the hardened samples, the influence of activator/precursor mass ratio, NaOH molarity, and two curing environments (Room temperature and 60°C) on the compressive strength, water accessible porosity, mass loss, and drying shrinkage were assessed. The results showed that a high Liquid/Solid ratio leads to a decrease in the compressive strength of the samples, while high NaOH molarity significantly improves the mechanical properties by reducing the porosity of the specimens. Moreover, alkaline silicate activator provides higher compressive strengths compared to the alkaline hydroxide activator, especially when the samples were cured at room temperature where a maximum 28days-compressive strength value of 105.28 MPa was achieved. For the samples activated using sodium hydroxide solution, the results revealed that their curing at 60°C promotes obtaining high initial-compressive strengths (7 days) before decreasing subsequently as a function of the curing time. As an indication, at high alkaline concentration (NaOH = 9M), a mechanical strength decline of 21% was recorded between a curing time of 7 to 28 days. Moreover, curing at 60°C induced high porosity, significant mass loss and high drying shrinkage. SEM analysis highlighted a dense, homogeneous microstructure without apparent defects, in particular for the samples where the alkali silicate activator was used.

Enhancement of kaolin clay soil for civil engineering application using rice husk ash and sawdust ash geopolymer cements

These days, good quality road construction materials are scarce and their haulage to the construction site is expensive. When unsuitable materials are encountered during flexible pavement construction, the most technical and economical option is always to improve them to meet design standards. One of these deficient materials mostly encountered in tropical regions is kaolin clay soils. Cement and lime that are traditional deficient soil improvement agents are on high demand therefore have kept the cost of engineering construction financially high. Thus, the use of agricultural wastes such as sawdust and rice husk as alternative construction materials will considerably reduce the cost of construction and as well mitigate the environmental hazards caused by the wastes and cement production. This study investigated and compared the performance of rice husk ash (RHA) and sawdust ash (SDA) geopolymer cements in improving the geotechnical properties of kaolin clay soil used for flexible pavement construction. All laboratory experimental tests were carried out in accordance with British Standard (BS) 1377 and BS 1924 for natural and modified kaolin clay soil samples respectively. Soil samples were mixed with geopolymer cement at stepped concentrations of 0, 4, 8, 12, 16 and 20% by dry weight of soil. Results indicated that the plasticity index value of the natural kaolin clay of 18.52% was reduced to 7.24% at 20% RHA geopolymer cement content. The unconfined compressive strength of the natural soil was improved by 600 and 400 % by RHA and SDA geopolymer cements respectively. It was concluded that the use of up to 20% RHA and SDA geopolymer cements can efficiently and eco-friendly improve kaolin clay for flexible pavement foundation purpose.

Evaluation of compliant walking locomotion models for civil engineering applications

This study aims to evaluate the suitability of the spring-loaded inverted pendulum (SLIP) model and three of its upgrades for modelling pedestrians in civil engineering applications. Model equations in Cartesian coordinates have been derived for the four SLIP-based models and they have been presented in ready-to-use format. The input parameter space that produces the stable periodic gait has been identified and relevant gait parameters (step frequency, average speed, and dynamic load factor) have then been evaluated against the measured parameter space characterising the pedestrian population. The results indicate that the original SLIP model has multiple drawbacks. Adding roller feet was found to increase the estimates of average walking speed when compared with the SLIP model. Adding damping brings more substantial benefits of improved coverage of the step frequency and dynamic load factor parameter space. Dimensional analysis was found to be a useful means of modelling a new pedestrian having either a new body mass or leg length. In summary, the analysis suggests that inclusion of leg damping in the model is crucial for achieving realistic estimates of the step frequency and dynamic load factor, while modelling foot geometry brings improved estimates of the walking speed.

Capture of CO2 through phosphogypsum and lye residues from the olive industry

A new carbonation procedure is presented to recycle waste from phosphoric acid production, known as phosphogypsum (PG). The PG is treated with lye (NaOH solution) used in the olive industry instead of commercial NaOH. Chemical analyses confirm that the reaction of these two industrial by-products shows very good carbonation efficiency. In addition, it has also been confirmed that the radionuclides present in the starting PG are mostly transferred to the solid by-product. The concentration of hazardous trace elements present in these solid by-products is low enough to allow their use in civil engineering applications. Therefore, this procedure can be a new management strategy for PG and waste streams from the olive industry and can be explored to exploit the potential of the PG by-product as a CO2 sequestration agent. In addition, it improves the economy of the process and mitigates the environmental impact of discharging of these caustics because it results in a neutral pH residual liquid.

Investigation on triaxial compressive mechanical properties of ultra high toughness cementitious composites with high strain capacity

Ultra high toughness cementitious composites (UHTCC) with significant strain capacity and high toughness is expected and potentially utilized to improve the performance of engineering structures under complex loadings. This study discusses the triaxial compressive behavior of UHTCC tested under seven different confining pressures with the maximum normalized confining pressure reaching 0.51. The obtained results indicate that the deviatoric strength, peak axial strain and peak lateral strain of UHTCC increase substantially with increasing confining pressure. Among these, the peak axial strain-confining pressure curve exhibits a clear nonlinear increasing trend. For the stress-strain curves, almost no softening phenomenon was observed when the normalized confining pressure reached only 0.425. The William-Warnke and Power-Law failure criterion are found suitable for describing the triaxial characteristic. The toughness index well reflects the significant energy absorption capacity of UHTCC. Based on the experimental results, UHTCC is expected to perform well in important civil and military engineering application which is potential to resist multi-axial loadings.

Piezoelectric Materials in Civil Engineering Applications: A Review.

This review presents the important applications of piezoelectric materials in civil engineering in recent years. Studies on the development of smart construction structures have been carried out by using materials such as piezoelectric materials around the world. Piezoelectric materials have attracted attention in many civil engineering applications, as a result of their capability of generating electrical power when subjected to a mechanical stress, or of generating mechanical stress when subjected to an electric field. In civil engineering applications, piezoelectric materials are used in energy harvesting not only in superstructures but also in substructures, control strategies, the creation of composite materials with cement mortar, and structural health monitoring systems. With this perspective, the civil engineering applications of the piezoelectric materials were reviewed and discussed, especially for their general properties and effectiveness. At the end, suggestions were made for future studies using piezoelectric materials.

New approach to junction efficiency analysis of hexagonal geogrid using digital image correlation method

Geosynthetics are commonly used in many civil engineering applications. At the same time, intensive development of these materials is being carried out. Therefore, it becomes more and more important to correctly determine the mechanical parameters of geosynthetics in laboratory tests. This is especially important for more complicated hexagonal geogrids. This article presents the results of the laboratory research carried out to evaluate the junction efficiency of hexagonal geogrid under static load by analyzing deformations of geogrid junctions and ribs. A new approach to determination the efficiency is given by the newly defined strain junction efficiency coefficient based on the true principal strains. In the laboratory tests the digital image correlation (DIC) method was used. This method allowed for the determination of displacements and strains of geogrid specimens in any direction and at any point. The results of the conducted research and analysis indicate that the proposed innovative junction effectiveness assessment method enables a better presentation of the geogrid performance at different levels of tensile load. In addition to the parameters given in the technical approval for this material, the proposed new strain junction efficiency coefficient can be an effective parameter for evaluating hexagonal geogrid performance at different strain levels.

An integrated characterisation of incineration bottom ashes towards sustainable application: Physicochemical, ecotoxicological, and mechanical properties

Environmental protection is a central concern regarding municipal solid waste incineration bottom ash (IBA) management, but the assessment of waste Hazardous Property HP14 (ecotoxicity) is still under debate. Civil engineering applications may be a suitable management strategy. This work aimed at evaluating IBA regarding mechanical behaviour and environmental hazardous potential, including a biotest battery for ecotoxicity assessment (comprising miniaturised tests), to explore its potential for safe utilization. Physical, chemical, ecotoxicological (Aliivibrio fischeri, Raphidocelis subcapitata, Lemna minor, Daphnia magna, Lepidium sativum), and mechanical (one-dimensional compressibility, shear strength) analyses were performed. The low leaching for potentially toxic metals and ions complied with European Union (EU) limit values for non-hazardous waste landfills. No relevant ecotoxicological effects were found. The biotest battery seems suitable for ecotoxicological assessment in the aquatic ecosystem, providing wide information on waste impact on different trophic/functional levels and chemical uptake routes, simultaneously involving short-duration tests and reduced amounts of waste. IBA presented more compressibility than sand, but its mixture with sand (30%:70%) was closer to sand compressibility. IBA (lower stresses) and the mixture (higher stresses) showed slightly higher shear strength than sand. Overall, IBA presented the potential for valorisation as loose aggregates from an environmental and mechanical viewpoint in a circular economy framework.

High-Temperature Behavior of Polyethylene-Terephthalate-Fiber-Reinforced Sand Concrete: Experimental Investigation

At ambient temperature, concrete exhibits excellent mechanical properties. However, understanding the behavior of concrete under high-temperature conditions is crucial, especially for civil engineering applications during fire incidents. The growing use of plastic-based products has led to a significant increase in polymer waste, posing environmental challenges. The valorization of this plastic waste in the form of fibers presents both economic and environmental advantages. This study focuses on the study of the behavior of sand concrete incorporating polyethylene terephthalate (PET) fibers with percentages of 1% and 2% at high temperatures (100, 300, 500 and 700 °C). Specimens are tested for residual mass loss, residual compressive and tensile strength. A complementary analysis of SEM makes it possible to confirm and better clarify the morphology of the concretes of sand before and after the rise in temperature. The results obtained from this study indicate that the residual resistance is reduced with the rise in temperature for all the concretes studied, except in the temperature range of 300 °C, in which a slight improvement in resistance is noticed. The incorporation of PET fibers in the test concretes does not enhance their residual behavior significantly. However, it does serve as an effective solution by reducing the susceptibility to spalling, by preventing cracking and by fulfilling a similar role to that of polypropylene fibers.

Prediction of displacement in Reinforced concrete based on artificial neural networks using sensors

Although structural health monitoring (SHM) is widely used in civil engineering, researchers are working to enhance its accuracy. In previous laboratory experiments, four types of sensors, namely force resisting sensor (FSR), piezoelectric sensor (PZS), microelectromechanical system (MEMS) accelerometer sensor, and flex sensor (FLS), were employed to predict load-displacement in Reinforced Concrete (RC) beams subject to monotonic two-point loading. Static loading was performed in the laboratory. The results demonstrated that MEMS sensors outperformed the other three sensors. Consequently, only MEMS sensors were used in the ANN model to predict the error percentage. This study compared the static results of previous experiments to those obtained from an Artificial Neural Network (ANN) model that used the beam's position and load as input parameters to predict displacement. The results revealed that the non-linear ANN model produced positive outcomes. Therefore, SHM is likely to utilize MEMS sensors in various civil engineering applications.

Evaluation of shear strength parameters of sustainable utilization of scrap tires derived geo-materials for civil engineering applications

The devastation caused by the illegal dumping and burning of tires has been staggering. In civil engineering, using tires engineering properties has become a major concern. For this investigation, the research used locally sourced tire chips and sand. Using tire chips sand as an alternative backfill material requires less pressure and has more improved properties than traditional backfill. Four specimens were utilized in this experiment: pure sand and sand mixtures containing 20%, 30%, and 40% tire chips, respectively. Both the Direct Shear and Triaxial Apparatus, two of the most important geotechnical tools, were used to compare and evaluate the shear properties of soil and sand tire chips. 50, 100, and 150 kPa Confining pressure and normal stress have been utilized to maintain a consistent stress level. Direct shear apparatus had a circular shape with an area of 16.62 cm2 and Triaxial shear apparatus had a height of 7.2 cm and a diameter of 3.2 cm. The stress-strain behavior of both apparatuses under ordinary loading and deviatoric stress was reported. The angles of internal friction (Φ′) and cohesion (c′) were measured for both equipment and specimens with and without tire chips, and the failure planes for direct shear and triaxial tests were reported. In both the direct and triaxial shear tests, 30% of the tire chips sand exhibit the best results, respectively. The addition of tire chips may significantly improve the toughness of the soil.

A Novel Higher-Order Zigzag Function Applied to Refined Unified Beam Theory for the Analysis of Composite Laminated Materials

Highly efficient materials and structures are becoming increasingly common in military, aeronautical, aerospace, mechanical, and civil engineering applications. Composite materials have been developed to address the need to combine two or more materials to achieve superior properties. Many structural elements, such as laminated beams, use composite materials, but an accurate mathematical model of the bending behavior is required due to the abrupt changes in material properties in the interlaminar zones. This accurate model can be achieved using zigzag theory. This theory is one of the most commonly used formulations for modeling laminated beams. This theory is an improvement of the equivalent single-layer theory as an additional term called the “zigzag function” is used to represent the variation in the axial displacement along the cross section. This paper proposes a novel high-order zigzag function in a sinusoidal format. Several higher-order beam theories are combined with the proposed functions, and their performances are compared with those of other functions in the literature. The results reveal excellent agreement between the proposed formulation and the reference solution as well as a more effective combination of zigzag functions and beam theory.

A grounded inerter-based oscillating TMD for suppressing harmonic and random vibrations

Inspired by the lightweight passive vibration control technology, in this work a new anti-vibration device is proposed to significatively improve the protection for stationary mechanical structures subjected to different kinds of vibratory loads. Such a device is herein termed as the grounded inerter-based two-degree-of-freedom tuned mass damper (GI-TDOF-TMD) composed by a grounded inerter and TDOF-TMD with rotational and translational motions, which controls the primary structure's dominant modal shape by using the synergistic dynamic effects of both devices. In order to fairly evaluate the GI-TDOF-TMD's vibration mitigation effectiveness with respect to other devices, the damped and undamped primary structure's nondimensional compliance and mobility transfer functions are firstly computed from a generalized mathematical model that considers four types of random and harmonic excitation inputs which are the following: force general case, base acceleration excitation, base displacement input and inertial force generated by the unbalance in rotary machinery. For harmonically excited mechanical systems, the H∞ performance measure is applied to minimize the maximum resonant peaks of the displacement and velocity dimensionless frequency response functions (FRFs). As the Extended Fixed-Points Technique (EFPT) is analogous to the H∞ criterion, quasi-optimal solutions are firstly computed to perfectly calibrate the FRF's invariant points. After performing this, the evolution of the FRF's control invariant frequencies revealed that GI-TDOF-TMD performs well at low inertance values. Therefore, the GI-TDOF-TMD's maximum control performance is obtained when the inerter's inertial force is the same as that yielded by the TMD's physical mass. In view of such a dynamic behavior, the GI-TDOF-TMD approximately provides 40% and 17% improvements when compared with respect to the classic dynamic vibration absorber (DVA) and TMD-inerter (TMDI), respectively. Then, the GI-TDOF-TMD's power dissipation capability is demonstrated by applying the H2 norm approach to the randomly excited damped mechanical structures. Additionally, it is also revealed through the stochastic energy balance that the GI-TDOF-TMD's internal power dissipation effectiveness is directly reflected on the minimization of the primary structure's kinetic energy. Moreover, for random inputs, the proposed device can broaden the effective operating bandwidth in approximately 45% and 19% when compared to the classic DVA and TMDI, respectively. Therefore, the GI-TDOF-TMD works better than the TMDI in terms of structural displacement and velocity response mitigation, which can be useful in civil engineering applications.

Strength prediction and optimization for ultrahigh-performance concrete with low-carbon cementitious materials – XG boost model and experimental validation

In recent years, supplementary cementitious materials (SCMs), as well as other unconventional materials [such as recycled glass powder (GP)], have gained much attention for the formulation of ultra-high-performance concrete (UHPC). Machine learning (ML) techniques have become more prevalent in everyday life in the current era of cutting-edge technology. Their applicability is readily evident in a wide range of areas, including civil engineering applications. This research aimed to develop, validate, and apply the novel XG Boost model to predict the characteristic compressive strength of UHPC containing recycled GP under normal moist curing conditions. Based on 309 datasets, the study developed and trained an ML model using different components, including four supplementary cementitious materials (silica fume (SF), fly ash (FA), quartz powder (QP), and glass powder (GP). The feature importance of the developed ML model was assessed using two methods (the Gini index and the SHAP values). Based on the validation datasets, the predicted-target data was within a 95% accuracy range. The optimized model was helpful tool for making accurate predictions over a wide range of data sets. It was observed from the results obtained that the most significant features were SF, water–binder ratio, water–powder ratio, and virtual packing density. The developed ML model and the tested mixtures showed a mean ratio of tested-to-predicted values of 0.956, with most data lying within a margin of error of 15%. As a result, an intuitive user interface was developed for optimizing UHPC systems, including SF, FA, QP, and GP.

Effect of particle size on the dynamic properties of tire derived aggregates (TDA)

This paper investigates the dynamic properties of tire derived aggregate (TDA) as a recycled material used in civil engineering applications. The effect of TDA type A particle size on the dynamic response is studied experimentally in detail, and the effects of hysteresis loop asymmetry, shear strain, and confining pressure on the shear modulus and damping ratio are also examined. Undrained strain-controlled cyclic triaxial tests with consolidation stresses ranging from 25 to 200 kPa and shear strains ranging from 0.1 to 10% are used to compare a granulated rubber (GR) specimens and TDA specimens with different maximum particle sizes. The dynamic response of TDA type A differs from that of granulated rubber, because of the larger particle sizes of TDA type A. Although TDA stiffness increases with increasing particle size, the damping ratio is insensitive to TDA particle size in the particle size range considered in this study. However, at all consolidation stresses, the damping capacity of GR is significantly lower than that of TDA. In particular, due to hysteresis loop asymmetry, conventional equations can significantly underestimate the shear modulus and damping ratio of TDA type A. Furthermore, a generalized MKZ model is proposed to estimate the maximum shear modulus at small strains (Gmax) and to predict shear modulus degradation curves for TDA type A with maximum particle sizes ranging from 19.1 mm to 50.8 mm. Comparisons of these shear modulus degradation curves to data reported in the literature and to the experimental results of a TDA sample with a random particle size distribution show that the proposed generalized MKZ model can provide reasonable estimates of the shear modulus of TDA type A.

Mineralogical, pozzolanic and microscopic characterization of dolomite mine overburden

Waste generated during the cutting and processing of stones is a severe environmental problem. Using waste materials in civil engineering applications is beneficial for sustainable construction practices. The stone industry generates a very high quantity of overburden during mining processes. This overburden is discarded as its composition is not similar to that in the pure state. This study aims to characterize the dolomite mine overburden in its native state. This characterization is based on mineralogical, pozzolanic and microscopic characteristics of dolomite overburden. The mineralogical characterization was done using XRD and XRF analysis. XRD tests showed the presence of dolomite [CaMg(CO3)2] and Silica Oxide (SiO2) in significant compositions. The predominant presence of 30.54 % of Calcium Oxide (CaO), 18.71 % Silica Oxide (SiO2) and 7.6 % of (MgO) was determined by XRF analysis. Frattini and Strength Activity Index (SAI) tests were performed to check the presence of pozzolanic properties in the material. Frattini test results showed the non-pozzolanic/inert nature of overburden. The inert nature of dolomite overburden was confirmed by SAI test results. The modified mix failed to fulfill the criteria of 75 % and 85 % strength of the control mix after 7 and 28 days of curing. The microscopic analysis was carried out by SEM analysis. SEM images showed the irregular shape and rough surface texture of dolomite overburden. The pozzolanic characterization proves that the dolomite mine overburdened can't be used as a cementitious material. Its application can be tested for filler material or as a replacement for coarse/fine aggregates in concrete and mortar mixes. It can also be tested as filler material in bituminous mixes or stabilizing agent in soil stabilization.

Development of self-healing soil-cement systems subjected to freeze-thaw cycles

Many civil engineering applications utilize soil–cement systems. However, deterioration of soil–cement systems due to repeated freeze–thaw cycles is a main concern for civil engineering applications. Freezing and thawing cycles can have a significant impact on the strength and permeability of soil–cement systems. This durability issue has a significant impact on the sustainability. Therefore, projects that use soil–cement systems may damage if subjected to freeze–thaw cycles. It increases the price of maintaining and repairing soil–cement systems. The study addressed in this paper primarily focuses on soil–cement systems that are vulnerable to freeze–thaw cycles. This study investigated different soil–cement systems for different freeze–thaw cycles of 1, 3, 5, and 10 with varying cement percentages (10%, 15% and 20% by weight of soil). By adding MgO powder, the soil–cement system was developed in this study. MgO powder increased the unconfined compressive strength by 6–47%, enhancing its capacity for self-healing. Maximum strength of 13% is observed at 10% cement content after 10f-t cycles. More generally, these smart systems allow for the construction of stronger, more resilient, and less prone to freeze–thaw degradation for engineering applications.

Flexural Behaviour of GFRP-Softwood Sandwich Panels for Prefabricated Building Construction.

Studies have shown that the proper selection of core materials in sandwich structures improves the overall structural performance in terms of bending stiffness and strength. The core materials used in such systems, such as foam, corrugated, and honeycomb, are frequently applied in aerospace engineering. However, they are a costly option for civil engineering applications. This paper investigates the bending performance of the proposed GFRP softwood sandwich beams assembled using pultruded GFRP with adhesive connection methods for potential applications in prefabricated building construction. The ultimate load capacity, load-deflection responses, failure modes, bending stiffness, load-axial-strain behaviour, and degree of composite action were experimentally evaluated. The effects of varying shear-span-to-depth ratios a/d between 2 and 6.5, as well as different timber fibre directions of the softwood core, on the overall structural performance were clarified. The results showed that changing the timber fibres' orientation from vertical to longitudinal shifted the failure mode from a brittle to progressive process. Moreover, the adhesive bonding was able to provide full composite action until the failure occurred. Finally, numerical modelling was developed to understand failure loads, deformation, failure modes, and strain responses, and to evaluate bending stiffness and composite action. The results showed satisfactory agreement with the experiments.