Crack Load Research Articles

Load transfer of small-diameter GFRP and stainless steel doweled-joints in slabs-on-ground

Large diameter steel and glass fiber-reinforced polymer (GFRP) dowel bars are commonly used in rigid concrete pavements in highways for load transfer across joints to combat the concrete deterioration due to corrosion of steel dowels. Small-diameter GFRP dowel bars can be used at the expansion joints in slabs-on-ground, walkways, industrial floors and concrete-lined channels, which are not subjected to heavy traffic loads. This study investigated the performance and behavior of small-diameter GFRP dowels. GFRP dowels with three diameters (14 mm, 16 mm, and 38 mm) and stainless steel dowels (12 mm dia.) were embedded across a 25 mm-wide joint in a test slab with overall dimensions of 1500 × 750 × 200 mm3. The variables of the study were the type of dowel material (GFRP and stainless steel), the diameter of GFRP dowels, the spacing of the dowels (200 mm and 250 mm c/c), and the type of loading (monotonic and cyclic). The slabs were loaded up to the failure of the joints under a concentrated load applied at the edge of the joint. The performance of the dowel-jointed slab specimens was investigated based on the cracking and ultimate loads, modes of failure, and load-displacement response. The ability of the small-diameter dowel bars to transfer displacements across the joint was quantified using the quantitative measures of joint effectiveness (E), load transfer efficiency (LTE), and relative deflections (Δ). Failure of the specimens with 14 mm and 16 mm diameter dowels occurred predominantly due to shear failure of the dowels before the cracking of concrete. However, for the specimens with large-diameter GFRP dowels and the stainless steel dowels, failure was associated with cracking of the concrete. A smaller spacing of the GFRP dowels and a longer embedment length gave a stiffer load-displacement response. Reducing the spacing from 250 mm to 200 mm resulted in a 4.1-fold reduction in relative deflection under the AASHTO H10 design wheel load (∼35.6 kN). Increasing the dowel length had no significant effect on the load-carrying capacity of the dowel-jointed slabs. Cyclic load tests on the specimens revealed that the joint effectiveness (E) and the load transfer efficiency (LTE) of GFRP dowels were within the AASHTO and ACPA limits up to a concentrated load higher than the AASHTO HL93 dual tandem-axle wheel load (∼55.6 kN).

Innovative Flexural Repair Technique of Pre-Damaged T-Beams Using Eco-Friendly Steel-Fibre-Reinforced Geopolymer Concrete

This paper presents an innovative flexural repair technique for pre-damaged reinforced concrete T-beams using eco-friendly steel-fibre-reinforced geopolymer concrete (SFRGPC). The study considers various parameters such as repair layer depth, location and configuration, and the use of additional reinforcement in one beam. The beams were preloaded to 50% of their ultimate flexural capacity. Extensive measurements were taken, including crack initiation and propagation, crack width, initial stiffness, load deflection, peak loads, ductility index, and strain values. The structural performance of the repaired T-beams under flexural loading was predicted using an analytical model. The repaired beams showed an increase in carrying capacity, stiffness, and ductility, but the failure mode was identical to the control samples. The study shows that SFRGPC shows great promise as a technique for not only repairing pre-damaged reinforced concrete beams but also for their strengthening. The best results were obtained with three-sided jackets with fibrous geopolymer concrete only, resulting in a load-carrying capacity increase of 25.8% compared to reference T-beams. The bonding between SFRGPC and existing concrete was effective, with no slippage or disintegration at the interface. The repaired beams’ structural behaviour and performance under flexural loads were successfully predicted using the analytical model, with a precision of about 98%.

Effect of local openings on bearing behavior and failure mechanism of shield tunnel segments

Local failures (loss of concrete or reinforcement) can severely compromise the bearing capacity of shield segments, damaging the tunnel structures. To investigate the effects of local openings on the bearing behavior and failure mechanism, four full-scale bending tests were conducted on specimens with different opening positions and diameters; monitoring of load, displacement, and concrete strain was performed during loading. The test results reveal that both the opening position and diameter significantly influence the bearing characteristics of the segment. The failure process includes four sequential stages distinguished by three critical loads, namely the cracking, failure, and ultimate loads. Subsequently, the numerical model of the local failure segment was established using the elastoplastic damage constitutive relation of the concrete and verified by inversing the full-scale test results. Based on the numerical model, parametric analyses were performed to comprehensively investigate the influences of the opening position, concrete loss, and reinforcement loss on the bending capacity. Furthermore, an analytical model was proposed, indicating that the opening position is the primary factor decreasing the bearing capacity, followed by the opening diameter and reinforcement loss. The results of this study can provide a theoretical basis for the safety assessment and remedial design of subway shield tunnels under extreme breakthrough conditions.

Experimental and Numerical Study of Strengthening Prestressed Reinforced Concrete Beams Using Different Techniques

This study aimed to evaluate the static response of prestressed reinforced concrete beams strengthened in their flexure and shear properties using different strengthening techniques, steel plates, and externally bonded woven carbon fiber fabric (WCFF). The experimental work involved testing twenty large-scale prestressed reinforced concrete beams with a length of 3000 mm, and cross-sections measuring 400 mm in height and 200 mm in breadth were cast in the factory and tested in the laboratory. Four beams without prestressing served as the reference beams; two unbonded pre-tensioned beams served as the control beams, and the remaining fourteen beams were strengthened with steel plates and externally bonded woven carbon fiber fabric (WCFF). Eight of the beams were strengthened with 4 mm thick steel plates and tested under a monotonically increasing load with manual readings recorded. The remaining six beams were strengthened with 0.5 mm thick WCFF and tested under a monotonically increasing load with manual readings recorded. The variables considered included the strengthening techniques (FRP composite sheets, steel plates), the types of strengthening (slices, U-shaped), and the flexural and shear capacities of the strengthened beams. All the implemented strengthening techniques yielded enhancements in both the flexural and shear strength outcomes of the beams compared to their respective controls. The most significant increase in load capacity, whether in terms of ultimate load or first crack load, for the prestressed concrete beams’ flexure properties occurred when strengthening with U-shaped steel plates. Additionally, the greatest reduction in deflection at the point of reaching the maximum load for the prestressed concrete beams, in terms of their flexure properties, was observed when strengthening with U-shaped steel plates. Similarly, the maximum load increase for the prestressed concrete beams, in terms of their shear properties, was achieved through strengthening with U-shaped woven carbon fiber fabric wrapping. Furthermore, a finite element model was created to simulate various experimental specimens. The finite element model’s results exhibited harmony with the experimental results, affirming the efficacy of the presented finite element model.

Experimental and numerical study on the seismic behavior of groove grouting precast concrete shear walls with different joint types

A groove grouting precast concrete shear wall (GGPCSW) subjected to seismic performance tests was explored in this research. Four full-scale specimens were designed for use in quasi-static experiments. These specimens included three GGPCSWs with different joint types (i.e., a horizontal joint, a vertical joint, and a combination of horizontal and vertical joints) and one reference cast-in-place reinforced concrete shear wall (CIPRCSW). The failure modes, failure process, hysteresis curves, bearing capacity, stiffness degradation, and ductility of the GGPCSWs were clarified. The experimental results revealed that all shear wall specimens failed in the flexural-shear failure mode. The crack distribution, load capacity, energy consumption, and stiffness degradation of the GGPCSW with a horizontal joint were found to be basically the same as those of the CIPRCSW before the displacement angle reached 1/100. The positive load capacity of the GGPCSW with a vertical joint was 22.5% greater than that of the CIPRCSW under the same conditions. It is noteworthy that the peak load of the GGPCSW with a combination of horizontal and vertical joints was basically the same as that of the GGPCSW with a vertical joint, while the ultimate displacement was 14% less than that of the GGPCSW with a horizontal joint. Furthermore, the GGPCSWs demonstrated a comparable level of ductility to the CIPRCSW, meeting the necessary deformability criteria. Finally, a series of numerical analyses were completed to investigate the skeleton curves, the distribution of the concrete damage, and the stress distribution of the steel bars. The findings were basically consistent with the test results, and further parametric investigations of GGPCSWs were performed.

Comparative Analysis of Reinforced Concrete Beam Behaviour: Conventional Model vs. Artificial Neural Network Predictions.

This research aims to conduct a comparative analysis of the first crack load, flexural strength, and shear strength in reinforced concrete beams without stirrups. The comparison is made between the conventional model developed according to the current design code (ACI building code) and an unconventional approach using Artificial Neural Networks (ANNs). To accomplish this, a dataset comprising 110 samples of reinforced concrete beams without stirrup reinforcement was collected and utilised to train a Multilayer Backpropagation Neural Network in MATLAB. The primary objective of this work is to establish a knowledge-based structural analysis model capable of accurately predicting the responses of reinforced concrete structures. The coefficient of determination obtained from this comparison yields values of 0.9404 for the first cracking load, 0.9756 for flexural strength, and 0.9787 for shear strength. Through an assessment of the coefficient of determination and linear regression coefficients, it becomes evident that the ANN model produces results that closely align with those obtained from the conventional model. This demonstrates the ANN's potential for precise prediction of the structural behaviour of reinforced concrete beams.

Long-term shear performance of concrete beam with carbon fiber-reinforced composite grid stirrups under sustained loadings and seawater immersion

Using carbon fiber-reinforced composite (CFRP) grid stirrups to replace traditional steel stirrups in reinforced concrete (RC) beams can effectively improve the corrosion resistance of structures in marine environments. In this study, the durability of RC beams with CFRP grid stirrups under the coupled effects of sustained loads and immersion in seawater was studied. The sustained loads were set at 24% and 48% of the ultimate bearing capacity of the RC beam, and the specimens were immersed in artificial seawater at room temperature for 90 days, 180 days, and 360 days, respectively. The crack load and shear capacity of the beam were measured at the scheduled time. The initial stiffness of the beam decreased as the immersion time increased, and the higher the sustained load was, the lower the initial stiffness of the conditioned beam. The contribution of the CFRP grid stirrup to the shear load capacity after the cracking load was reached was more significant than that before. The effects of the 48% sustained load on the ultimate tensile strain of the CFRP stirrup were more significant than those for the 24% sustained load. Both immersion and sustained loading improved the cracking load and shear capacity of the beam, and the contribution of sustained loading to the shear capacity decreased as the immersion time and the sustained load level increased. Equations were proposed for predicting the shear strength of RC beams with CFRP grid stirrups under sustained loading and seawater immersion.

Investigation of the Flexural Behavior of Bacterial Concrete Beams

Abstract Bacterial self-healing concrete is an eco-friendly and superior treatment technique that has efficient bonding capacity and compatibility with concrete compositions. It is capable of filling deep microcracks and healing the crack autonomously by calcium carbonate precipitating phenomenon which results in sustainable construction materials. The purpose of this research is to investigate the use of microorganisms Bacillus Subtilis to improve the mechanical properties and the efficiency of self-healing of reinforced concrete beams for two types of concrete, reactive powder concrete (RPC), and lightweight self-compacting concrete (LWASCC), by two methods of addition (direct addition, and encapsulation). The experimental program consists of casting six simply supported beams tested under monotonic and repeated loading. Incorporate bacteria and the precursor (calcium lactate) in concrete mixtures show an improvement in compressive strength, splitting, and flexural strength by up to 21.74 %, 10.92 %, 21.21 % by encapsulation method, and 17.7 %, 18.0 %, 20.84 % by direct addition. In addition, there is an enhancement in the first crack load and ultimate load. Microscopical image demonstrated that calcium carbonates had been deposited in the crack up to 1.0 mm width by bacterial activity within 32 days.

Study of mixed-mode fracture in functionally graded material using an adaptive phase-field fracture model

This work systematically investigates the mixed-mode fracture propagation in functionally graded materials. The crack trajectory and load–displacement responses were effectively simulated using the mixed-mode phase field approach in combination with an adaptive mesh refinement technique. The mesh refinement is carried out using quadtree decompositions, and the elements with hanging nodes are handled as n−sided polygons. The adaptive implementation is validated by solving benchmark problems from the literature. The adaptive technique demonstrates greater computational efficiency by significantly reducing the number of elements without compromising the accuracy of the solution. This study provides insight into how fracture propagation behavior is influenced by gradient profile, material gradation, crack location, energy release rate, and displacement configuration in uni-directional and bi-directional functionally graded material. Remarkably, it is found that the peak load on the load–displacement graph changes noticeably, and the fracture path remains constant despite variations in the critical energy release rate. Notably, the results show that materials with lower fracture toughness have an early failure when studying a center fractured plate. This thorough examination deepens our understanding of the propagation of mixed-mode cracks and provides insight into improving the analysis and design methodologies for functionally graded materials.

Fracture toughness of AlSi10Mg alloy produced by direct energy deposition with different crack plane orientations

The fracture and tensile behaviors of the AlSi10Mg alloy processed by Direct Energy Deposition were investigated. Three-point bending fracture toughness and tensile specimens were tested at room temperature along different crack plane orientations and loading directions. Before being machined and tested, the printed samples were subjected to heat treatment at 300 °C for 2 h to relieve the residual stresses. Microstructural and fractographic analyses were performed to investigate the fracture mechanisms and the crack propagation paths for each crack orientation. Significant differences in the fracture toughness were observed among the crack plane orientations. Specimens with cracks oriented in the X-Y direction featured the highest fracture toughness values (JIc = 11.96 kJ/m2), whereas the Z-Y crack orientation (perpendicular to the printing direction) performed the lowest fracture toughness values (JIc = 8.91 kJ/m2). The anisotropy in fracture toughness is mainly related to a preferential crack propagation path along the melt pool boundaries. At melt pool boundaries, pores are preferentially placed, coarsening of the microstructure occurs and there is higher Si content, leading to that area being less ductile and less resistant to crack propagation.

Determination of SIFs and application of a SIF-based fracture criterion for concrete-rock interface under sustained loading

This study proposes an effective method to determine the stress intensity factors (SIFs) of the interface crack considering the viscoelasticities of the bilateral materials and verifies the feasibility of the initial fracture toughness-based fracture criterion for the concrete-rock interface under sustained loading. Firstly, low-level sustained loading tests were conducted on the composite concrete-rock specimens with respect to two interface roughness degrees and two sustained load levels less than the initial cracking load. Then, an implicit creep equation was employed to characterise the viscoelasticities of bilateral materials and then calculate the mechanical responses of the concrete-rock interface in the low-level sustained loading test. The SIFs of the interface crack under sustained loading were determined by using the elastic strain energy density ahead of the crack tip. By averaging the SIFs over the radius of the core region of the crack tip, the representative SIFs under sustained loading were obtained. The test results indicated that the SIFs showed decreasing tendencies under sustained loading, and the initial fracture toughness can be considered as a material property of the concrete-rock interface. The initial fracture toughness-based fracture criterion was verified to be feasible to determine the initial cracking status of the concrete-rock interface under sustained loading. In addition, due to the reductions of the SIFs under sustained loading, additional loads were required to compensate the losses of the SIFs, leading to the enhancement of the initial cracking loads after experiencing the sustained loading.

Rehabilitation of reinforced concrete deep beams by near-surface-mounted steel reinforcement

Abstract This article describes an experimental investigation of the behavior of reinforced concrete deep beams repaired by near-surface-mounted (NSM) steel bars. The first beam was loaded under a two-point load up to failure, and the other six deep beams were loaded to 0.4 and 0.75 of ultimate load. Then, they were repaired by NSM steel bars. The bar orientation and angle were the main variables in these beams. The primary goal of this study is to determine whether it is possible to restore the reinforced concrete deep beam with shear reinforcement to its full load-carrying capacity by NSM steel bars as the method of repair. All deep beams were tested with a shear span-depth ratio of 0.8. The test findings showed that the NSM steel repair bars were very effective in restoring the loaded deep beams’ full capacity. Moreover, NSM steel bars enhanced the original deep beams’ strength capacity from 4.16 to 19.44%. The ultimate load, mechanisms of failure, load–crack width distribution, and load–deflection profile are tracked as results.

Influence of the Oriented Configuration of the BarChip Fibre Polypropylene to the Ductility Factor of the Reinforced Concrete Beam

Abstract
 Bending and shear strength of fiber reinforced polimer concrete beams was studied in this research project. The reinforced concrete beam behaves in brittle structure in the certain reinforcement configuration. BarChip fibre polypropylene as the material for enhancement of the ductility factor is applied to the concrete beam. Three types of BarChip fibre configuration were examined: randomly spreading, placing at the mid-span area, and concentration on the tension zone. The experimental program included five beam specimens. Two of the beams were control specimens in which one was reinforced with no fibre, while the other one did not have any Barchips polypropylene. Each one of the other three specimens was reinforced with one of the above mentioned fibers by 0,4% volumetric ratio. Investigating the following issues for medium-high concrete strength was the goal of this study. In order to determine whether adding 0.4% volumetric ratio of polypropylenes as additional bar reinforcement in beams would provide adequate strength and stiffness properties comparable to reinforcing steel used as minimum bar reinforcement, it was necessary to first assess the effectiveness of each type of oriented fiber configuration on the bending strength, then to look into each beam's bending strength, shear strength, toughness, crack patterns, and near ultimate load crack width. The findings demonstrated that the bending capacity of the beam specimens was raised by all three types of polypropylene configuration more than by the beam reinforced with the fewest amount of bar reinforcement. Additionally, some of the employed fibers may cause failures other than pure shear. It is reccomended to spread the polypropylene within the tension zone of the reinforced concrete beam on the bottom mid span.
 Keywords: Fibrous Concrete, Polypropylene, Ductility, Reinforced, Beam

Determining SCC resistance of stainless steel claddings in high- temperature water by constant load crack growth tests and slow strain rate tests

Stress corrosion cracking (SCC) behaviors of 309 L and 308 L weld overlays are characterized in oxygen-free and oxygen-bearing high-temperature water using slow strain rate tests (SSRTs) and crack growth rate (CGR) tests with compact tension specimens. There is no apparent SCC indication on 308 L, while local SCC is observed on 309 L after SSRT in oxygen-free water. The SCC sensitivities of 308 L and 309 L increase with the increase of dissolved oxygen (DO) content, while 308 L shows relatively higher SCC resistance than 309 L in water with 200 ppb and 8000 ppb DO. SSRT and CGR test results show a similar effect of DO concentration on SCC of 309 L and 308 L. The fracture surface of 309 L exhibits extensive intergranular SCC, while 308 L shows only local interdendritic SCC after CGR tests. The crack tip blunting decreased the CGR in the low alloy steel. The highly island-shaped δ-ferrites and moderate strain hardening in 308 L contribute to its SCC resistance over 309 L.

Seismic behavior of autoclaved aerated concrete masonry walls reinforced with glass-fiber geogrid

Reinforcing horizontal mortar joints with steel bars can improve the seismic performance of autoclaved aerated concrete (AAC) masonry walls. Nevertheless, the diameter of steel bars can require a large thickness of the mortar joints, which in turn results in the thermal bridging effect. Glass fiber geogrids (GFGs) can be employed to replace steel bars to reduce the thickness of mortar joints, and thus can mitigate the thermal bridging effect. Despite considerable advancements in understanding the mechanical performance of GFGs in masonry walls, their effect on the seismic performance of AAC walls remains unknown. Therefore, this study investigates the effect of different GFG configuration rates on the seismic performance of AAC masonry walls using reciprocating load tests. Furthermore, the effect of different vertical compressive stresses on the seismic performance of GFG-reinforced AAC masonry walls was studied via comprehensive finite element simulations. The test results show that the ultimate load-bearing capacity and ultimate displacements of the wall specimens were enhanced as the GFG configuration rate increased, approaching that of benchmark specimens reinforced with steel bars. On the other hand, the cracking and ultimate loads, along with ultimate displacements of GFG-reinforced AAC masonry walls were significantly improved compared to those of the unreinforced AAC masonry walls. It was also evidenced that the crack formation, failure mode, ductility and energy dissipation capacity of the specimens simulated through the finite element method were highly comparable to that of experimentally tested specimens. Accordingly, the vertical compressive stresses were in the range of 0.1 MPa ∼ 0.6 MPa, while the seismic performance of GFG masonry walls was improved with the increase in vertical pressure. The results of the current study confirm that embedding GFG in horizontal mortar joints can delay the cracking of AAC masonry walls and improve their seismic performance. Ultimately, an empirical equation was developed to calculate the seismic shear strength of GFG-reinforced AAC masonry walls.

Determination of the KIC Fracture Toughness of the X210Cr12 High-Strength Material

Purpose: It is an important problem that the machines become unusable due to the deformation of the machine elements produced before the planned time. In this study, it was aimed to determine the KIC value of X210Cr12, which is a high strength material. In this way, more accurate load values can be used in the design.Methods: In the experimental study to determine the KIC value, the sample geometry, the crack depth, the load-dependent parameters and calculations and some conformity checks were carried out. Experimental system; KIC consists of 3-point flexure specimens, a press, an electronic circuit capable of detecting the change in load crack opening, and a logger.Findings: In the study, the loads were determined from experimental graphs. Subsequently, load-crack opening values were determined. With these data, the KIC values were calculated as 719,7 and 839,7 MPa.mm1/2 as the minumum and maximum values, respectively.Conclusion: The experimental graphs are in the form of curves that break abruptly with unstable crack propagation without showing plastic deformation. There is no study in the literature on the KIC value of X210Cr12 and it has been determined that it has a low KIC value compared to the high-strength steels studied. It is valuable to determine the KIC value, as fracture problems may occur in designs prepared with the material. The results of the study are data at room temperature.

Experimental and numerical studies of reinforced concrete stair beams strengthened with steel bars and plates

The bends under sagging moments in a Reinforced Concrete Stair Beam (RCSB) in staircases may be damaged because of improper detailing design or construction; therefore, they need to be strengthened or repaired. The structural behavior of strengthened RCSBs has not been investigated adequately. This paper presents experimental and numerical investigations on the flexural strengthening of RCSBs with bends under sagging moments. Tests on RCSBs were undertaken that were strengthened by using either the Near-Surface Mounted Steel Bars (NSMSBs) or the Externally Bonded Steel Plates (EBSPs). Three steel materials were employed, including Steel Bars (SBs), Steel Sheets (SSs) and Stainless-Steel Plates (SSPs). The test program and outcomes are described in detail of six full-scale strengthened RCSBs loaded up to collapse. A finite element model is developed employing ABAQUS to simulate the performance of the tested RCSBs. It is found that the utilized strengthening techniques effectively enhance both the cracking and ultimate loads in addition to the energy absorption capacity. The agreement between simulations and experiment is good, suggesting that the model of nonlinear finite element analysis can be used with confidence to perform further parametric instigations.

Flexural behavior of the hollow slab girders strengthened with ultra-high performance concrete: Field full-scale experiment and analysis

Due to high strength and well durability, ultra-high performance concrete (UHPC) can be designed to strengthen damage hollow slab girder. The main objective of this study is to evaluate reinforcement feasibility of compression zone of hollow slab girder via field full-scale experiments and finite element (FE) analysis. To this end, UHPC layer was firstly proposed to reinforce top plate of damaged hollow slab girder. Then, four-point bending tests were conducted to investigate flexural behavior of hollow slab girder with/without UHPC layer. FE models were developed to simulate bending failure process of hollow slab girders. The deflection, crack propagation and stress distribution of hollow slab girders were analyzed as well as failure modes. The results show that UHPC layers can significantly improve flexural stiffness of hollow slab girder, and it results in an increase of 11.5% in cracking load and 23.7% in ultimate load, respectively. Moreover, reinforced girder exhibits well ductility and relatively high flexural bearing capacity. Furthermore, the parameter analyses were performed to investigate the effects of the thickness of UHPC layer and prestress on flexural behavior of reinforced girder. The results show that the prestress significantly affects the ductility and cracking load. Whereas, it seems to be independence of ultimate load. Finally, theoretical analysis was performed to obtain calculation formulas, which determine cracking and ultimate loads of reinforced hollow slab girder. Overall, this study has verified effectiveness of proposed reinforcement method in improving stiffness and flexural bearing capacity of hollow slab girder.

Accuracy verification of fast adaptive galerkin finite volume solver for thermal and mechanical load crack propagation in triangular meshes

This study presents the details of the Galerkin finite volume method for triangular unstructured meshes and its application for the fracture analysis of 2D elasticity problems under simultaneous thermal and mechanical loading. The heat diffusion and elasticity equations are discretized using the Galerkin finite volume method (which, due to omitting matrix manipulation calculations, computations are considerably faster than FEM and XFEM Solvers). The maximum tangential stress criterion is presented after briefly describing the interaction integral formulation used to calculate the stress intensity factors in thermo-mechanical problems. The accuracy of the computed results of the present strategy under thermo-mechanical loads is demonstrated using some benchmark test cases. First, a thermal stress analysis of a plate with an inclined central crack under thermal boundary conditions is performed. Second, the development of a crack under mechanical stress boundary conditions is modeled. Third, crack propagation under both thermal and mechanical boundary conditions is simulated. The present modeling strategy's results are compared with those reported in previous numerical works to verify the accuracy. The stress intensity factors and predicted crack trajectories are utilized to assess the accuracy of computed results and investigate the quality of crack simulation by the proposed numerical method.

Flexural Behavior of Normal and High Strength Self-Curing Self- Compacted Concrete Beams of Local Materials

In some construction industries, there are difficulties in achieving the required concrete compaction, Self-compaction is an alternative option. Working with self-compaction self-curing concrete requires a unique approach. This study aims to examine the possibility of producing self-compacting concrete with normal and high self-cure rates. This research observed how both the self-curing and self-compacting concrete behaved under normal and high-strength conditions. Two stages were prepared for this investigation. The first stage of this research studied the effect of a curing agent on the fundamental characteristics of both normal-strength and high-strength self-compacting concrete, with the aim of achieving self-curing self-compacting concrete. The primary variables of this study include the grade of concrete, the type of curing agent, the reinforcing bars, and the dosage of these variables. In the second stage, reinforced concrete beams were cast with one of the two proposed concrete types, and their behavior was studied. The findings were analyzed in terms of the beginning cracking loads, the ultimate loads, and the crack patterns of the testing beams. According to the results, both the normal-strength and the high-strength varieties of self-curing self-compacting concrete are effective in providing structural features, which are absent from the processes of curing and compacting. Curing chemicals are utilized to mitigate the process of water evaporation in self-compacting concrete, hence enhancing the water retention capabilities of self-compacting concretes that possess enough hardened concrete characteristics.