Point Load Research Articles

Collapse analysis of masonry arches and domes considering finite friction and uncertainties in compressive strength

Within the context of the lower bound theorem of classical limit analysis, the collapse of stone masonry arches and domes characterized by finite friction and uncertain finite compressive strength is addressed. Self-weight is considered, along with a live point load applied at the crown. A multi-constrained funicular approach based on the concept of force densities is implemented to provide the maximum static load multiplier for any assigned value of the friction coefficient and of the compressive strength. The numerical method, which takes into full account the stereotomy of blocky stone structures, is validated by using a novel version of the semi-analytical Durand-Claye’s stability area method. Two different types of brickwork are considered in the investigation, addressing the compressive strength as a random variable with prescribed log-normal distributions. Due to the limited availability of data to elaborate probabilistic models for the angle of friction, the effect of this mechanical parameter on the probability of failure of the blocky structures is assessed by developing a set of fragility curves. For each discrete value in a representative range of friction coefficients, a Monte Carlo investigation is performed by iteratively applying the funicular method considering samples of the random variable that describes the compressive strength. The retrieved load multipliers are processed to estimate the probability of failure for any given magnitude of live load, which depends on the value of the friction coefficient. An insight into the collapse modes occurring in the masonry arches and domes under examination is provided, as well.

Experimental investigation of dowel action in reinforcing bars using refined measurements

AbstractIn typical reinforced concrete design, reinforcement is designed to carry axial forces, but it can also resist transversal forces by dowel action. This is usually neglected for simplicity's sake in the design phase, but it can be accounted for either explicitly in mechanical models or implicitly in empirical relationships. Furthermore, there are cases where the connection between various concrete elements explicitly depends on dowel action, as for example, in connections between precast elements or between two concrete parts cast at different times. On the other side, dowel action can have a negative impact on the fatigue resistance of reinforcing bars subjected to cyclic loading, because of the local stress concentrations near interfaces due to relative movements, either in sliding or in opening of cracks not perpendicular to the bar. For the assessment of the remaining capacity of existing structures, improved models of the behavior are needed, including realistic models of the behavior of concrete, steel and their interfaces. The aim of the present paper is to provide a contribution to a better understanding of dowel action by two test series. The first series focused on the behavior of the dowel: the concrete specimens with the embedded bars were placed in a custom‐made test setup and subjected to monotonic or low stress‐level cyclic actions with a longitudinal and a transversal crack opening component, up to developing the full plastic capacity of the dowel and rupture at the peak of catenary action. The measurement system included tracking the displacement field at the surface of the concrete and the strains in the dowel by optical fibers glued on its surface. The latter measurements allow to derive the internal forces in the reinforcing bar and deformed shape of the bar as well as the contact pressure between the bar and the surrounding concrete. The results show a strong dependency on the test variables: diameter of the bar, imposed crack kinematics and angle between the bar and the crack. The second test series looked more closely at the behavior of concrete underneath the bar, in the presence of a point load introduced at various locations into concrete through a reinforcing bar. A comparison of the test results with existing models shows a general good agreement and some aspects that deserve to be improved.

Prediction of Rock's Brittleness and Dynamic Properties Utilizing Effective Artificial Intelligence Approaches

This research aims to determine the brittleness index (BI) and engineering properties of limestone specimens. In addition, this study evaluates the effect of moisture on the developed models to predict the BI and shear wave velocity (Vs), based on the point load index (Is50), dry and saturated tensile strength (Ts-d and Ts-s), and porosity. Gaussian process regression (GPR), multilayer feed-forward neural network (MFFNN), and multiple linear regression (MLR) predictive models were utilized. Microscopic examination of the limestone specimens revealed that calcite is the predominant mineral. It was observed that samples with higher calcite content exhibited greater brittleness and strength properties while having lower porosity. The results obtained from the MLR analysis demonstrated that it is possible to accurately forecast the brittleness index (BI), as well as the dry and saturated shear wave velocities (Vs-d and Vs-s) at the specific sites under investigation. The moisture effect on developed models showed that Vs prediction in dry conditions (Vs-d) was less accurate compared to the saturated conditions (Vs-s). Conversely, the relationships developed for estimating the BI in dry conditions exhibited higher accuracy. The analysis of all model assumptions using MLR indicated that the models could be reliably utilized. However, the MFFNN and GPR methods were found to be more conservative in estimating these properties. Moreover, the study identified the best transfer function and training algorithm for predicting Vs and BI. The evaluation metrics, such as R2 and RMSE revealed that GPR demonstrated higher precision compared to MFFNN and MLR.

Study on Static Mechanical Properties and Numerical Simulation of Coral Aggregate Seawater Shotcrete with Reasonable Mix Proportion

This study aims to explore the static mechanical characteristics of coral aggregate seawater shotcrete (CASS) using an appropriate mix proportion. The orthogonal experiments consisting of four-factor and three-level were conducted to explore an optimal mix proportion of CASS. On a macro-scale, quasi-static compression and splitting tests of CASS with optimal mix proportion at various curing ages employed a combination of acoustic emission (AE) and digital image correlation (DIC) techniques were carried out using an electro-hydraulic servo-controlled test machine. A comparative analysis of static mechanical properties at different curing ages was conducted between the CASS and ordinary aggregate seawater shotcrete (OASS). On a micro-scale, the numerical specimens based on particle flow code (PFC) were subjected to multi-level microcracks division for quantitive analysis of the failure mechanism of specimens. The results show that the optimal mix proportion of CASS consists of 700 kg/m3 of cementitious materials content, a water–binder ratio of 0.45, a sand ratio of 60%, and a dosage of 8% for the accelerator amount. The tensile failure is the primary failure mechanism under uniaxial compression and Brazilian splitting, and the specimens will be closer to the brittle material with increased curing age. The Brazilian splitting failure caused by the arc-shaped main crack initiates from the loading points and propagates along the loading line to the center. Compared with OASS, the CASS has an approximately equal early and low later strength mainly because of the minerals’ filling or unfilling effect on coral pores. The rate of increase in CASS is swifter during the initial strength phase and decelerates during the subsequent stages of strength development. The failure in CASS is experienced primarily within the cement mortar and bonding surface between the cement mortar and aggregate.

Influence of joint types on rigidity of Chebyshev elastic gridshells: A parametric analysis

Elastic gridshells (EGS) have many applications in the field of architecture. Built according to Chebyshev net geometry, the Chebyshev EGS (CGES) is a famous kind of EGS; since an arbitrary three-dimensional CEGS can be transformed into a planar state without any stretching strain. Due to its tremendous potential application in novelly deployed structures, the rigidity of CEGS is an important mechanical property to be investigated.In this study, using the analytical and finite element methods, the influence of joint types and gridshell parameters on the rigidity of CEGS subjected to point loads is studied in detail. The joint types are classified as pin joints, semi-rigidity joints, and rigid joints. A robust relation between rigidity and gridshell parameters is proposed, including Young's modulus, rod diameter, size of CEGS, joint stiffness, and rod numbers. Further, the above relation is nondimensionalized. The dimensionless rigidity is only related to the two dimensionless parameters, which are dimensionless joint stiffness and rod number. The rigidities of CEGS on four types of surfaces are calculated to verify the above relation, and satisfactory agreement is obtained. Therefore, the proposed relationship of rigidity is confirmed to be accurate and efficient for a wide range of parameters.

A laboratory study on the durability of limestone wastes in harsh environments for their suitability as aggregate in concrete

One of the critical environmental issues in the Chegeni area (Lorestan Province, western Iran) is the production of a large volume of limestone wastes during the quarrying operations. Releasing limestone wastes in the areas neighboring the quarries has caused visual damage to the environment, and adverse effects on the quality of the soil, running water, and groundwater used for agricultural and drinking water purposes. One solution to this issue can be recycling limestone wastes to produce building materials. In the present study, a comprehensive laboratory program is planned for the durability evaluation of the limestone wastes under harsh environments for their suitability as aggregate in concrete. For this purpose, five aging tests, including freeze-thawing (F-T), salt crystallization (SC), acid attack (AA), wetting-drying (WD), and heating-cooling (HC), were conducted on the limestone sample up to 60 cycles. After every 10 cycles, the physico-mechanical characteristics of the sample, including porosity (n), Brazilian tensile strength (BTS), point load index (PLI), and P-wave velocity (Vp) were determined. Moreover, the pores structure modification of the sample subjected to aging tests was examined through scanning electron microscopy (SEM). Data analyses revealed that the sample is highly vulnerable to the AA and SC processes but is durable against FT, WD, and HC actions. These results were in good agreement with the SEM data such that the sample exposed to AA and SC underwent more changes in their pore structure compared to FT, WD, and HC. Among the physico-mechanical characteristics, the Vp and PLI had the highest and the lowest accuracy, respectively, in the durability evaluation of the sample exposed to aging tests. Based on the data analysis, limestone wastes can be used as aggregate in concrete in environments with the possibility of FT, WD, and HC. However, this type of concrete is not suitable for conditions with occurrences of the AA and SC. Finally, in addition to reducing the environmentally harmful impacts of the study area, using limestone wastes as aggregate in the construction of concrete can also be a practical solution for sustainable development from an economic viewpoint. The results of the present study can be used for assessing limestone wastes produced in other areas of Iran and the world.

Flexural Behaviour of RC Beam with Pond Flyash and ESP FlyAsh

The use of Supplementary Cementitious Materials (SCM) such as Fly ash, Granulated Slag and Silica fume as a replacement for Portland cement in concrete presents one viable solution with multiple benefits for the sustainable development of the construction industry. Out of various supplementary materials, Fly ash is the most widely used material worldwide. Fly ash has excellent structural and durability characteristics. The pore filling effect and pozzolanic properties of Flyash improves the properties of fresh and hardened concrete. In addition to the cost saving bythe replacement amount of cement; it reduces co2emission during the manufacture of Portland cement. In the present investigation, a controlled beam and six number of ESP flyash and Pond flyash beams of size 200 x 100 x 1700 mm were cast. This paper deals with the investigation on the flexural behaviour of beam with pond flyash and ESP (Electro static precipitated) flyash at various cement replacement levels of 4%, 6%, and 8% and the results are compared with controlled beam. The flexural test was conducted to determine the ultimate load carrying capacity of the beams and their corresponding mid span deflection, load point deflection, crack pattern, Stress vs strain are measured. The flexural strength of ESP flyash is increased 24.76% for 8% replacement level and pond flyash is increased 10.97 % for 6% replacement level than controlled beam respectively. This study revealed that the replacement of cement by flyash concrete provides higher compressive strength & flexural strength compared with controlled concrete.

Interfacial debonding in a thin plate bonded to a rigid substrate with a circular hole

Mode I fracture is a prevalent failure mode in adhesively bonded joints. This paper presents analytical and numerical solutions for the mechanical interaction of a thin plate bonded to a rigid substrate with a circular hole. Utilizing the bilinear cohesive law, the proposed solution is designed for the bonded joints subjected to uniformly distributed load and point load, respectively. The interfacial normal stress distribution and load-displacement response undergo three distinct stages: the initial elastic stage, followed by the elastic-softening stage, and culminating in the elastic-softening-debonding stage. The load-displacement response of the joints subjected to uniformly distributed load and point load diverges after debonding occurs. The load-carrying capacity of the former decreases rapidly, while the latter exhibits an opposite trend. Finite element (FE) simulation is conducted for numerical validation, demonstrating excellent agreement between the proposed model and FE results. The paper concludes by discussing the influences of hole radius, bond length, and the properties of the adhesive layer and thin plate on load-displacement response and the ultimate load. The findings suggest that higher bond strength and larger fracture energy of the adhesive, along with thicker and stiffer thin plates, contribute to achieving higher load-carrying capacity in bonded joints. Additionally, a longer bond length improves the load-carrying capacity for the joint subjected to the point load, with minimal impact for uniformly distributed loads once the bond length exceeds the effective bond length.

SimLOD: Simultaneous LOD Generation and Rendering for Point Clouds

LOD construction is typically implemented as a preprocessing step that requires users to wait before they are able to view the results in real time. We propose an incremental LOD generation approach for point clouds that allows us to simultaneously load points from disk, update an octree-based level-of-detail representation, and render the intermediate results in real time while additional points are still being loaded from disk. LOD construction and rendering are both implemented in CUDA and share the GPU's processing power, but each incremental update is lightweight enough to leave enough time to maintain real-time frame rates. Our approach is able to stream points from an SSD and update the octree on the GPU at rates of up to 580 million points per second (~9.3GB/s) on an RTX 4090 and a PCIe 5.0 SSD. Depending on the data set, our approach spends an average of about 1 to 2 ms to incrementally insert 1 million points into the octree, allowing us to insert several million points per frame into the LOD structure and render the intermediate results within the same frame.

Additive manufacturing as a resource-saving alternative in the manufacturing process of marine gearbox housing

ABSTRACT Marine gearbox housings are large components of several metres in length and tonnes of weight. The conventional manufacturing process is a time-consuming and elaborate process with the necessity to oversize the components from a load point of view. This results in a redundant amount of energy and resources for manufacturing. In contrast, wire arc additive manufacturing (WAAM) offers the possibility to realize a load- and weight-optimized design and provides an energy- and resource-efficient alternative in the manufacturing of marine gearbox housings. It has been shown that this additive manufacturing process provides the potential of 41% energy reduction and 36% material reduction compared to the iron cast manufacturing process. This is due to the modification of the load flow and the use of the hybrid manufacturing production as well as the possibility to include bionic structures in the gearbox design.

Evaluation of Ni-Cu Ore from Zapolyarnoe Based on Mineralogical and Physical Properties before and after Comminution

For the effective comminution and subsequent enrichment of mineral ores, comprehensive knowledge of their mineralogical and physical properties is required. Using an integrated methodology, this study evaluated samples of polymetallic Ni-Cu ore from Zapolyarnoe, Russia. Several analytical techniques were utilised, including optical microscopy, microindentation with Vickers geometry, the Point Load Test, and Mineral Liberation Analysis (MLA). The purpose of this study was to determine mineral associations, physical features, and enrichment during jaw crusher comminution. The acquired properties included the Point Load Strength Index, Vickers Hardness Number, and fracture toughness. The MLA method characterised seven fractions in terms of particle size distribution, degree of liberation, association, and modal mineralogy. Magnetite, pyrrhotite, pentlandite, and chalcopyrite were calculated in terms of wt% and their textural features. The enrichment of each ore phase in fractions with particle sizes smaller than 400 µm was determined. The influence of this enrichment was discovered to be correlated with various textural and structural parameters, such as intergrowth, grain size, and crack morphologies after indentations. In addition, the chromium content of magnetite contributed to an increase in the fracture toughness values. Despite the complexities involved, even limited samples of materials provide valuable insights into processing behaviour, emphasising the importance of considering mineralogical parameters in comminution studies.

Risk Assessment of Radial Distribution Systems using Modified Jelly Fish Search Algorithm to analyse the Performance Indices

One of the essential techniques for figuring out Power Distribution System performance is reliability evaluation. With time, the range of methods for assessing reliability has grown, and the distribution system's evolution has also become more intricate. The likelihood of a network failing grows with time once it begins to function, especially if it is used for an extended period. Reliability indices have been evaluated using different algorithms such as Particle Swarm Optimization (PSO), Genetic Algorithm (GA) and various modified versions of algorithms. The Jelly Fish Search Algorithm has been used in various power system applications such as to determine the most cost-effective way to dispatch generating units' loads, integrate Distributed Generation (DG) units, track the maximum power of photovoltaic systems, and determine optimal power flow solutions, among other uses. The performance indices for the Radial Distribution System (RDS) have not been evaluated using JFSA.Variation of performance indices with respect to unavailability has not been discussed in the literature. Here an attempt is made to analyse the variation of the indices with the unavailability. The proposed algorithm is evaluated first on 3 load point radial distribution system and the computations are performed on the popular IEEE-RBTS Bus2 test system. Based on the output it is observed that for the both the systems the behaviour of the indices with respect to the unavailability is in similar fashion. The equations are derived for the performance indices using the Minitab. With the equations obtained the Performance indices values can be predicted for the given unavailability value. It is the better appropriate method for the assessing the performance indices of Radia Distribution System.

Experimental platform for studying energy regeneration in electric vehicle powertrains

Investigation into the energy consumption in electric vehicles (EVs) plays a pivotal role in determining their autonomy and assessing the electric system performance across diverse operational scenarios. This study focuses on the concept of energy regeneration, encompassing the recovery and storage of kinetic mechanical energy during braking or descent in EVs. Employing control systems in power electronics becomes necessary to establish a seamless workflow across operational quadrants to ensure efficient energy regeneration in an electric machine functioning as both a motor and a generator. To seamlessly integrate new technologies into practical applications, it is essential to conduct thorough evaluations in laboratories prior to deployment. This paper introduces an experimental platform specifically designed to analyze energy consumption and storage in EVs by emulating their powertrains in a controlled laboratory environment. The platform comprises key components for emulating the powertrain of a single-motor electric vehicle with single-axle traction, including a power converter configured in two quadrants, an energy storage system, a primary rotating electric machine, and a mechanically coupled point load torque (another motor). This paper provides a detailed guide on implementing such a laboratory and for facilitating the testing of diverse motor technologies and controllers under varied operational conditions. This comprehensive approach allows for the assessment of electromechanical system efficiency, focusing on both energy recovery and comprehensive control of electric power converters. Validation tests conducted under urban conditions and on steep terrains demonstrate the effectiveness of the platform in analyzing the energy efficiency of both the induction machine and the power controller.

Predicting base resistance of super-long piles using a random forest model: A case study from Ho Chi Minh city

The prediction of the base resistance for long piles is usually challenging because of the impact of material characteristics and the influence of the nature of the surrounding soil. Artificial intelligence models have been applied in various geotechnical engineering fields, and significant results have been achieved. Based on a well-instrumented static load test dataset (1131 data points) from various projects in the soft soil area of Ho Chi Minh City, this study established a random forest (RF) model considering five input parameters, including the applied load, load point displacement, axial stiffness, standard penetration test value of the soil beneath the pile toe, and the distance from the load point to the pile toe. Twenty percent of the data was designated as the test set, which was used to make predictions using the established model. The results show that the RF model has good predictive performance in terms of prediction accuracy and reliability. A sensitivity analysis of the input factors provided a deeper understanding of the base resistance mechanism, which is important in pile foundation design practice.

In-site Investigation of Rock Mass Structure Effect on Tunnel Smooth Blasting Quality

Smooth blasting controls tunnel excavation contours and rock stability; however, it can lead to overbreaks and underbreaks due to rock mass anisotropy. Studying the Zigaojian tunnel of the Hangzhou-Huangshan Expressway, this research examined the effect of rock mass structure on smooth blasting quality. Four rock mass structure types–massive, layered, and cataclastic–were determined through manual measurements, three-dimensional scanning, point loading tests, and wave velocity measurements. The blasting overbreak and underbreak of the tunnel section were measured using a tunnel section laser distance measuring instrument, and the relationship between the blasting overbreak and rock mass structure type, surrounding rock grading, structural plane spacing, structural plane number, uniaxial compressive strength, and density was studied using multiple regression analysis. The results show that the overbreak area and maximum overbreak increase as the integrity of massive, massive, layered, and cataclastic rock masses decreases. The intersection of the rock mass structural plane and tunnel section was overbroken. The overbreak is positively correlated with the rock structure type, surrounding rock grading, and structural plane number and negatively correlated with the uniaxial compressive strength, density, and structural plane spacing. The results of this study can provide a reference for smooth blasting in similar projects.

Research on Damage Evolution in Ultra-thin Sheet Material under Deep Drawing and Ironing Process

In this paper, the effect of damage induced in deep drawing and ironing processes on the subsequent service performance of deep drawn cups was investigated. To obtain the cups with different amount of deformation damage, three kinds of drawing tests including one-stage deep drawing, two-stage deep drawing, and two-stage deep drawing and ironing were conducted using a 0.3 mm interstitial-free steel sheet. With help of the DF2015 ductile fracture model, the damage evolution of the drawn cups was calculated. Moreover, ring specimens cut from the side walls of the drawn cups were tested in a specially designed tension platform. The load F max and displacement x corresponding to the maximum load point, and the difference in displacement dx from the maximum load point to the fracture initiation point of ring tensile specimens were used as indicators to evaluate the effect of accumulated damage on the subsequent service performance of the parts.

Effect of high-temperature thermal fatigue on mode I fracture toughness of gabbro

Investigating variations of rock fracture toughness after high-temperature thermal fatigue is greatly significant for developing deep geothermal resources. This study investigated the mode I fracture toughness of gabbro after high-temperature fatigue treatment by heating a cracked straight-through Brazilian disc (CSTBD) gabbro specimen to 200, 400, 500, and 600 °C, followed by 100 thermal cycles. Additionally, acoustic emission (AE) and digital image correlation (DIC) were used to monitor the failure process of gabbro. The results showed that the peak load, fracture toughness, and fracture energy of gabbro decreased with the increased temperature and number of cycles, which was most significant at 500 and 600 °C. Under mode I loading, cracks developed along the loading direction and connected with the prefabricated crack. Additionally, the regions with higher von Mises equivalent strain (Evm) values were concentrated at the loading points and prefabricated crack of the rock sample. The degree of bending of the primary cracks increased, the number of secondary cracks increased, and the Evm values changed significantly as the temperature increased. The phase transformation of plagioclase feldspar at 450 °C and the oxidation of iron- and magnesium-containing pyroxene at 600 °C changed the internal structure of the rock. Cyclic treatment further exacerbated the thermal damage, developing microcracks within the rock and reducing fracture toughness significantly.

Integration of optimal power flow with combined heat and power dispatch of renewable wind energy based power system using chaotic driving training based optimization

Combined heat and power economic dispatch (CHPED) based optimal power flow (OPF) problem has been studied in this article using a new, practical approach based on chaotic driving training optimization (DTBO) (CDTBO). In the proposed technique (CDTBO), the chaotic based learning is integrated with DTBO to overcome the local optimal problem and inferior convergence speed of the existing algorithms. OPF is an important concern to retain the power system running effectively. In order to meet the demand for reasonably priced power generation with optimal power flow in transmission lines, the authors combined CHPED and OPF. Since fuel is changing daily in the current environment, using renewable energy sources to generate electricity economically is crucial. The renewable energy source like wind energy is integrated with thermal units for economic power generation with reducing the thermal fuel consumption of CHPED-based OPF system. The proposed technique implemented on CHPED based IEEE-30 bus system for renewable and without renewable energy sources with considering different cases. The suggested problem considering with valve point loading of thermal units, transmission losses and uncertainties of wind speed to address the non-linearity of the renewable-based CHPED-OPF system. Cost minimization, voltage deviation control, transmission losses minimization and stability index are the single objectives of the prospective system. Furthermore tested on multi-objective functions for simultaneously minimization of cost with emission and simultaneously minimization of active power loss with voltage profile. It is observed that the proposed CDTBO technique helps to reduce the cost by 2% and 12.8% for renewable based system as compared to non-renewable system for multi-objective function. The robustness of the proposed solution has been verified by implementing the statistical analysis on two systems with least variation of mean and optimal values of cost with the tolerance of less than 0.0035%. A comparison has been made with recent well known optimization techniques to address the superiority of the suggested CDTBO algorithm.

Mesoscopic Analysis of Fatigue Damage Development in Asphalt Mixture Based on Modified Burgers Contact Algorithm in Discrete Element Modeling.

This study is aimed at examining the mesoscopic mechanical response and crack development characteristics of asphalt mixtures using the three-dimensional discrete element approach via particle flow code (PFC). The material is considered an assembly of three phases of aggregate, mortar, and voids, for which three types of contact are identified and described using a modified Burgers model allowing for bond failure and crack formation at contact. The laboratory splitting test is conducted to determine the contact parameters and to provide the basis for selecting three different load levels used in the indirect tensile fatigue test and simulation. The reliability of the simulation is verified by comparing the fatigue lives and dissipated energies against those from the test. Under cyclic loading, the internal tensile and compressive force chains vary dynamically as a response to the cyclic loading; both are initially concentrated beneath the top loading strip and then extend downward along the loading line. The compressive chains are oriented roughly vertically and develop an elliptic shape as damage grows, while the tensile chains are mostly horizontal and become denser. An analysis based on the histories of the numbers of different contact types indicates that damage mainly originates from bond failures among the aggregate particles and at the aggregate-mortar interfaces. In terms of location, cracking is initiated below the loading point (consistent with observations from the force chains) and propagates downward and laterally, leading to the macrocrack along the vertical diameter. The findings provide a mesoscopic understanding of the fatigue damage initiation and propagation in asphalt mixture.

The influences of type, length, and volumetric fraction of fibers on the direct shear strength of the fiber-reinforced concretes

Besides the common modes of failure including compressive, tensile, and bending in concrete structures, cracking and failure due to the shear is also considered as a significant and hazardous mode of failure. The shear failure mode can be observed in structural elements such as deep beams, locations having high point loads, connection cores of beams and concrete columns, short columns, punching shear in slabs and foundations, etc. However, the direct shear strength of the fiber-reinforced concretes has seen limited studied. Hereupon, this study aims to experimentally investigate the influences of the type, length, and various volumetric fractions of the steel fiber (SF) and polypropylene (PP) fiber on the compressive strength, the tensile strength, and specifically on the direct shear strength of the fiber-reinforced concretes. To this end, four different mixture design schemes of the plain concrete were examined by adding PP and SF with lengths of 3 cm, 5 cm, and their half-half combination with volumetric fractions of 0.5 %, 1 %, and 1.5 % to measure the compressive strength (the cubic sample), the tensile strength (the cylindrical sample), and the direct shear strength (the prismatic sample) of the concrete specimens. In addition, the plain concrete specimens as the witness specimens were built to compare with fiber-reinforced ones. The experiments were not only performed for 20–25 MPa concrete strength category, but were also executed for 25–30 MPa. The constructed concrete specimens were exhaustively surveyed in terms of the contribution of the fibers, the failure patterns in various specimens, the force-displacement diagrams in shear, the maximum displacement in specimens, the aspect ratio of the fibers, and the shear ductility index in various specimens. The obtained results indicated that, with increasing the length and volumetric fraction of the fibers (i.e., the aspect ratios), the compressive, tensile, and direct shear strengths have been subsequently augmented in the concrete specimens. Moreover, the strain and ductility of the concrete specimens have also been enhanced. Remarkably, in most tests, the SF-reinforced specimens have excellent performance compared with other specimens. However, the specimens containing the PP fibers have not considerably improved the compressive and direct shear strengths of the concrete specimens.