Steel Grid Research Articles

Characterization of Neutron Irradiator as a Source of Reference Radiation Field for Calibrating Dosemeters and Doserate Meters at PSI Laboratory

A new neutron calibration laboratory has been installed at the Paul Scherrer Institute in Switzerland. The calibration laboratory has been equipped with a newly developed neutron irradiator with two calibration benches, remote control instruments and related ancillary equipment for calibrating dosemeters and doserate meters. The actual dimensions of the calibration laboratory are 2.0 m (H) X 6.8 m (W) X 12.6 m (L). On the steel grid at a height of 2 m from the basement floor, two calibration benches are installed. A transport channel is installed in the middle of the benches for the transfer of the radiation sources. The radiation sources are moved from the safe position of the irradiator to the reference irradiation position using an air pressure unit. The reference position is at a height of 1.2 m from the grid floor. The neutron irradiator is equipped with two Am-Be sources. Characterization of neutron radiation field has been calculated in detail by the MCNPX neutron transport code as well as energy distribution of neutrons and contribution of scattered neutrons. Experimentally, it was measured with a neutron/gamma digital spectrometric system equipped with a stilbene detector. The quality of the neutron radiation field has been characterized by ambient dose equivalent rate and the shape of the Am-Be spectra has been verified with the ISO-8529 standard.

Structural Behavior of Full-Scale Novel Hybrid Layered Concrete Slabs Reinforced with CFRP and Steel Grids under Impact Load

Reinforced concrete two-way slabs are important elements in the construction field, and their impact response under drop-weight impact is a complex mechanical issue that can cause the collapse of heavy structures. Previous research has documented the analysis of conventional steel-reinforced concrete slabs under impact loads. However, the investigation of layered hybrid concrete composite flat solid slabs reinforced with carbon-fiber-reinforced polymer (CFRP) rebars is an innovative subject. This paper examines the structural behavior of layered novel hybrid concrete composite flat solid slabs with a combination of reactive powder concrete (RPC) in the top layer and normal concrete (NC) in the bottom layer, reinforced with internal CFRP or traditional steel bars in the tension zone, under an impact load test. For this purpose, ten full-scale square flat solid slab samples with a 1550 mm length and a 150 mm depth were fabricated and divided into eight layered hybrid concrete samples with 50% RPC and 50% NC and two samples cast with NC only. The impact tests were carried out using a hardened steel cylindroconical impactor (projectile) with a height of 650 mm and a diameter of 200 mm, a flat nose diameter of 90 mm, and a total mass of 150 kg released from two different heights of 5 and 7 m. The variables considered were the types and ratios of reinforcement, as well as the free-drop weight and height. The experimental results obtained showed that layered RPC flat solid slabs are superior in resisting and sustaining impact forces and also have fewer scattered parts when compared to NC flat solid slabs. Additionally, the flat solid slab samples reinforced with CFRP bar grids were overall more resistant to impact loads, by an average of 19%, compared to flat solid slabs with steel bars and showed lower deflection, by an average of 10%, compared to the other flat solid slabs.

Study on Effective Length Factors of the Members in a Sustainable Assembled Steel Grid Shear Wall

Study on Effective Length Factors of the Members in a Sustainable Assembled Steel Grid Shear Wall

Computing irregular hypar-based quad-mesh patterns for segmented timber shells

Hyperbolic paraboloids, “hypars,” are special types of ruled surfaces. Their geometric properties provide them with loadbearing and stabilizing capacities, as well as distinct esthetic qualities. These attributes become evident in numerous applications in buildings, in many of which concrete or timber is used for the construction of the hypars. Hypars could also be relevant in the context of circular construction and design for disassembly, and the upcycling of construction waste. Due to the geometric simplicity of straight lines, which generate ruled surfaces, hypar-based structures can be designed and built with relatively simple means. They can consist of self-similar or even identical elements, which could facilitate their reuse.Compared to other types of ruled surfaces, such as conoids, hypars have the advantage of being doubly ruled, meaning that structural grids of straight elements can be formed. This paper investigates another interesting property, which is the possibility of creating flat-quad meshes by diagonally connecting the intersection points of the generatrices. This property has been previously described by other scholars, some of which explored its applicability for glass-clad steel grid shells. In this research, we focus on its potential for segmented timber shells that can serve as stand-alone structures, or as modular and reusable building parts, such as façade or roof components. The reusability of such modular units could be achieved by using reversible joints between them.More specifically, our research investigates the design space of construction systems based on such components via computational design and optimization algorithms, such as the memory limited Broyden–Fletcher–Goldfarb–Shanno (LBFGS) algorithm with automatic computation of the gradient, within the Julia programming environment. By applying principles and methods of differential geometry, we study hypars with irregular tilings, enabling the integration of panels with diverse proportions, shapes and sizes, as they can occur in wood production waste. By reducing construction waste, the work aims at reducing the negative environmental impact of the building construction sector. Moreover, irregular tilings could enable a more customized design of acoustic qualities and offer visual variety in segmented hypar based timber structures.The here presented studies show that the proposed optimization method provides a good fit of many tiles to rhombi, particularly when the steepness is not too large. We also show that optimizing towards rectangles provides better results. Overall, the results support the initial assumption that irregular rulings could be a means of adapting to both homogeneous and diverse material stocks.

Modal–based uncertainty quantification for deterministically estimated structural parameters in low-fidelity model updating of complex connections

Modeling complex joints in structures entails significant time and effort, necessitating simplifications. Epistemic uncertainties arising from low-fidelity modeling can be quantified through probabilistic model updating. However, finding a surrogate physical model to represent simplified joint configurations poses challenges. Additionally, establishing a Bayesian formulation capable of incorporating structural parameters of connections is necessary. This study employs a validated simplifying parameterization approach for surrogate modeling of complex semi-rigid connections in a benchmark laboratory steel grid. It proposes a modal probabilistic Bayesian methodology to quantify uncertainties in the structure's joints. Three modal-based objective functions are utilized for finite element model updating. The modal properties of the structure are extracted by experimental modal analysis during an impact test, which will be utilized in the model updating process. Deterministic and probabilistic structural parameter estimations are integrated to enhance the robustness of the Bayesian technique. Furthermore, a guideline for selecting optimal hyperparameters is provided. Results demonstrate that utilizing deterministically estimated parameters as prior knowledge can facilitate and improve modal probabilistic model updating for structures with complex joints. Also, it is found that despite significant simplifications of joints, structural parameter tolerance around the maximum a posteriori estimate in surrogate models remains low.

Ultra-low cycle fatigue test study of bolted spherical joints in steel grid structures

During a catastrophic earthquake, bending and failure were exhibited in the bolted spherical joints, and these phenomena have obvious ultra-low cycle fatigue (ULCF) failure characteristics. To study the failure characteristics, hysteresis behavior, stiffness degradation, and energy consumption of bolted spherical joints, the ULCF test of bolted spherical joints specimens was carried out. The experimental study showed that the high-strength bolts experienced an ULCF failure process of bending, crack initiation, crack propagation, and instantaneous failure, and the fatigue life of the specimens was less than 20 times. The pinch phenomenon in the hysteresis curve of the specimen was significant, indicating that its energy consumption was poor. The energy-damage model of the specimens under cyclic displacement was derived based on the cumulative energy consumption. A damage assessment method for the specimen was proposed based on the energy-damage model and angle change characteristics of the specimen. This method provides a reference for damage assessment and repair design of bolted spherical joint grid structures after an earthquake.

Structural damage identification with output-only strain measurements and swarm intelligence algorithms: a comparative study

The identification of structural damage with the unavailability of input excitations is highly desired but challenging since structural dynamic responses are affected by the coupling effect of structural parameters and external excitations. To deal with this issue, in this paper, an output-only damage identification strategy based on swarm intelligence algorithms and correlation functions of strain responses is proposed to identify structures subjected to single or multiple unknown white noise excitations. In the proposed strategy, four different population-based optimization algorithms—particle swarm optimization, the butterfly optimization algorithm, the tree seed algorithm, and a micro search Jaya (MS-Jaya)—are employed and compared. The micro search mechanism is integrated into a basic Jaya algorithm to improve its computational efficiency and accuracy by eliminating some damage variables with small values for the identified best solution after several iterations. The objective function is established based on the proposed auto/cross-correlation function of strain responses and a penalty function. The effectiveness of the proposed method is verified with numerical studies on a simply supported beam structure and a steel grid benchmark structure under ambient excitation. In addition, the effect of the reference point, number of sensors, and arrangement of strain gauges on the performance of the proposed method are discussed in detail. The investigated results demonstrate that the proposed approach can accurately detect, locate, and quantify structural damage with limited sensors and 20% noise-polluted strain responses. In particular, the proposed MS-Jaya algorithm presents a more superior capacity in solving the optimization-based damage identification problem than the other three algorithms.

Визначення швидкості корозії основного конструкційного матеріалу сіток капілярних розділювачів фаз

The subject of this study is the corrosion processes that occur in the fuel tanks of spacecraft with a long service life, the engines of which operate on chemically aggressive fuel components (FC): nitrogen tetroxide (NT) and asymmetric dimethylhydrazine (NDMH). The goal is to determine the reduction of wire diameters and the increase of cell sizes of capillary phase separator grids (PSG) because of the corrosion effect of the main structural material of the 12X18H10T stainless steel grid. Task: establishing the presence, type, and rate of corrosion of the main structural material of the PSG nets. The methods used are as follows: to determine the presence of corrosion by studying the composition of substances found on the surface of the grids – X- ray fluorescence, X- ray structural, atomic absorption, potentiometric, turbodimetric, infrared spectroscopy, and chromato-mass spectrometry; to determine the type of corrosion-metallographic studies of mesh samples; to determine the rate of corrosion-measuring the geometric dimensions of mesh samples. The following results were obtained. The metal cations detected on the surface of the mesh samples correspond to the elements that make up the alloy of aluminum and steel - the main structural materials of the fuel tanks of launch vehicles; 12Х18Н10Т steel is not susceptible to local types of corrosion (pitting, intercrystalline, dot, contact, crevice, and stress corrosion cracking) in high-pressure and low-pressure tanks; the presence of a continuous (uniform) corrosion effect on the surface of the grid wires was established; dependences of changes in the main geometric parameters of the grids (wire diameters and cell sizes) over time were obtained, according to which the limits of the corrosion rates of stainless steel grade 12X18N10T in the liquid phase of NT and NDMG and in the gas phase were established; and coefficients of the maximum corrosion rate were calculated. Conclusions. The scientific novelty of the obtained results is as follows: for the first time, the presence, type, and rate of corrosion of the main structural material of the PSG grids because of their long-term operation (14...31 years) in the liquid phase of AT and NDMH and in the gas phase were determined using cross-methods.

Automated structural parameter estimation of semi-rigid complex joints in a benchmark laboratory steel grid by experimental modal analysis

The mechanical properties of joints may impact a system’s static and dynamic behavior. Since connections are usually complex, modeling their geometric details could take time and effort. Thus, joints of structures are often overlooked in model creation and calibration. Therefore, reliable analytical modeling of in-service structures requires accurate and efficient parameter estimation of the connections in their simplified models. However, joints are physically small parts of a system, and parameter estimation techniques may not be sufficiently sensitive to the variations of connections’ mechanical properties. This paper examines the finite element model updating of a laboratory steel grid focusing on the structural parameter estimation of its complex connections using modal data. The mechanical properties of the joints are parametrized by added mass and reduced rigidity. Therefore, several modified models with different combinations of heavier semi-rigid joints are developed. Each model is updated using two modal-based error functions, and the most representative updated model is selected. The results demonstrate how the grid modal outputs are influenced by updating the mass and stiffness of its connections. Moreover, mass and stiffness interactions of the grid joints in the parameter estimation procedure are illustrated. The updated models can efficiently simulate the structural behavior of the grid with increased confidence and reliability.

Advancing Shallow Tunnel Construction in Soft Ground: The Pipe-Umbrella Box Jacking Method

The development of modern cities has often led to increased traffic congestion and limited usable space. One effective solution to these problems is to construct roadway tunnels, which can expand urban space and alleviate traffic congestion. However, building large underpass tunnels in urban areas, especially in soft ground, presents technical challenges owing to its extensive environmental disturbance. The pipe-umbrella box jacking method offers a promising solution to these challenges as this method does not require breaking the ground from the surface or disrupting surface traffic. This study reviews the key techniques of the pipe-umbrella box jacking method for constructing large rectangular tunnels with small burial depths in soft ground. The study focuses on three main technical issues: pipe umbrella installation, soil face excavation, and box jacking control. Furthermore, two tunnel projects in Shanghai, China, are presented as case studies to showcase the construction challenges and countermeasures during box jacking tunneling with pipe-umbrella. Practical construction experience has revealed that the installation of the pipe umbrella before box jacking serves as an effective method of ground pre-support. However, its performance can be influenced by factors such as pipe installation deviation and inter-pipe connection design. Both open-face steel grid extrusion (SGE) shields and closed-face earth pressure balanced (EPB) shields can be used for soil excavation during box jacking, with different work modes resulting in distinct ground deformation patterns. Additionally, lubrication grouting has been found to effectively reduce friction resistance and affect vertical ground deformation. The study also examines the lessons learned from case studies and proposes optimization measures. This study can serve as a valuable reference for the tunneling industry, providing insights into the pipe-umbrella box jacking method and its application in constructing large rectangular tunnels in soft ground.

Physical and Numerical Models of Mechanically Stabilized Earth Walls Using Self-Fabricated Steel Reinforcement Grids Applied to Cohesive Soil in Vietnam

Mechanically stabilized earth (MSE) walls have been widely applied in construction to maintain the stability of high embankments. In Vietnam, imported reinforcement materials are expensive; thus, finding locally available materials for MSE walls is beneficial. This study examines the behavior of an MSE wall using local reinforcement materials in Danang, Vietnam. The MSE was reinforced by self-fabricated galvanized steel grids using CB300V steel with 3 cm ribs. The backfill soil was sandy clay soil from the local area with a low cohesion. A full-scale model with full instrumentation was installed to investigate the distribution of tensile forces along the reinforcement layers. The highest load that caused the wall to collapse due to internal instability (reinforcement rupture) was 302 kN/m2, which is 15 times greater than the design load of 20 kN/m2. The failure surface within the reinforced soil had a parabolic sliding shape that was similar to the theoretical studies. At the failure load level, the maximum lateral displacement at the top of the wall facing was small (3.9 mm), significantly lower than the allowable displacement for a retaining wall. Furthermore, a numerical model using FLAC software 7.0 was applied to simulate the performance of the MSE wall. The modeling results were in good agreement with the physical model. Thus, self-fabricated galvanized steel grids could confidently be used in combination with the local backfill soil for MSE walls.

Seismic retrofitting of RC columns using stainless steel grid-reinforced UHPC jackets in plastic hinge zone

This study aims to propose a new seismic retrofitting method for reinforced concrete (RC) columns in buildings with insufficient or flawed design in early standards by locally using stainless steel grid-reinforced ultra-high performance concrete (UHPC) jackets in the plastic hinge zone. For this purpose, pseudo-static loading tests were conducted on four rectangular columns with economical reinforcement ratios, including three retrofitted columns and one traditional RC column, and the effects of the number of stainless steel grid layers and the height of UHPC jackets were investigated. Additionally, a fiber-based finite element model was developed for the retrofitted columns and its accuracy was verified. The influence of other parameters not considered in the experiment, such as the axial compression ratio, UHPC jacket thickness and concrete compressive strength on the seismic performance of the retrofitted columns were also analyzed. The results demonstrated that the proposed retrofitting method effectively improves the seismic behavior of RC columns in a quick and cost-effective manner. The combination of stainless steel grids and UHPC jackets provided stable confinement for the internal RC columns, significantly reducing the damage in the plastic hinge zone and the residual displacements. Compared with the RC column, the ductility, bearing capacity and energy dissipation of the retrofitted columns were enhanced. Especially, the ductility coefficient of the specimens using a two-layer stainless steel grid increased by 27.19 %–36.56 %.

Experimental evaluation of cyclic performance of steel slag and grids of truck scrap tire as a novel reinforced ballast material

Introducing a novel ballast material based on reinforcing steel slag aggregates with strips of scrap tire can be beneficial due to decreasing the crushing and increasing the damping of the ballast materials. Moreover, recycling the two waste materials included in this novel ballast has a positive impact on environmental preservation. In this regard, the Waste Tire Reinforcement (WTR) consists of strips of truck scrap tire (385/80/R22.5) with a width of 70 mm utilized in grid shape (with various dimension grids of 21 ×7, 11.5 ×7, and 7 ×7 cm) as a reinforcement element. To evaluate the performance of suggested reinforcement with Steel Slag Ballast (SSB), a series of ballast box tests were performed up to 100,000 loading and unloading cycles with a magnitude and frequency of 30 kN and 3 Hz at three different levels of 5, 10, and 15 cm for WTR placement in ballast. The experimental results revealed that the WTR reinforcement with grids of 11.5 × 7 cm and a placement height of 5 cm (WTR11.5–5) has the best performance compared to other configurations. Compared to SSB without reinforcement, WTR11.5–5 may reduce breakage by more than 90% and increase the damaging ratio by 160%.

Flame synthesis of Fe3O4/Fe2O3 on stainless steel grid surfaces to improve anodic electrochemical properties

Flame synthesis of Fe3O4/Fe2O3 on stainless steel grid surfaces to improve anodic electrochemical properties

Effect of steel grid on enhancing seismic performance of bridge pier with low reinforcement ratio: Shaking table test and numerical simulation

The railway bridge piers with large cross section and low reinforcement ratio are easy to damage under earthquakes in China. The steel grid has been proved to be an effective strengthening method to improve the cyclic behavior using quasi-static test. In this study, shaking table tests were conducted to investigate the seismic response of three pier specimens. Experimental results indicated that the steel grid delayed the crack development and occurrence of uplifting-rocking phenomenon for the railway pier. For strengthened piers, about 7.5%-51.4% reduction, 9.1%-21.9% and 7.6%-27.4% enhancement is measured for displacement of pier top, acceleration of pier top and energy dissipation. To obtain the effect of design parameter variation of steel grid on seismic damage (i.e., the horizontal distance between steel grid and the surface of pier specimen, steel grid area and vertical spacing of steel grid), the numerical analysis mode of strengthened pier was established. The mechanical model of steel grid obtained by deriving the equivalent spring calculation method is used in the numerical simulation model. The results show that the horizontal distance variety between steel grid and surface of pier specimen has the most obvious impact to strengthening effect, while the vertical spacing of steel grid is the least. The smaller horizontal distance between steel grid and the surface of pier specimen, the higher steel grid area and shorter vertical spacing of steel grid are the most significant to reduce the different damage probability of the bridge pier.

Assessment of nanoplastic extraction from natural samples for quantification purposes

Plastic pollution poses an increasing threat to the whole ecosystem. Scientists recently realized that this pollution also occurs at the nanoscale. Nanoplastic monitoring is a real challenge and published data are scarce. Above the use of appropriate analytical instrument, one main obstacle is to quantitatively isolate the nanoplastic from larger particles in real samples. We propose a method based on the monitoring of polystyrene nanospheres following the polystyrene intrinsic fluorescence to assess the losses. Polymer-based membranes were tested for filtration, ultrafiltration and dialysis; important losses were observed. The isolation of the colloidal fraction is proposed using stainless steel grid with reduction of the losses. The ability of glass fiber filters to trap the nanoplastic was also evaluated as a mean to transfer the particle to the analytical instrument. As an illustration, a river sample was processed with the recommended protocol and the colloidal content monitored by nanoparticle tracking analysis. As a conclusion, we insist on the fact that it is absolutely necessary to evaluate nanoplastic extraction efficiencies for quantification purposes and we give recommendations to limit losses.

Stress Analysis and Structural Optimization of Steel–Concrete Joint of Zhonghua Road Bridge in Liaocheng

Based on Zhonghua Road Bridge in Liaocheng city, a single tower hybrid cable-stayed bridge, the stress of the steelconcrete joint of the girder is studied using the finite element method with the software MIDAS and ANSYS. The beam element model of the whole bridge is established in MIDAS CIVIL, from which the internal forces of the critical sections of the steel–concrete joint under six adverse conditions are obtained. Then, the results are applied in the refined solid-shell finite element model established in ANSYS. With the stress analysis, it is found that when the steel–concrete joint is used in the girder of the single tower cable-stayed bridge, both the compressive strength of concrete and the tensile strength of steel can be fully used, and the structural stiffness can be smoothly transferred through the two different materials in the joint, which makes the structural behavior more reasonable. The detailed stress analysis also shows that it is prone to generate considerable stress concentration at the corners and the connection between the steel lattice chamber and the pressure bearing plate, and the concentration can be avoided by local stiffening and smoothing of the chamfers. The sensitivity analysis of the web thickness in the joints and bearing plates showed that increasing the thickness of the intermediate web would lead to a moderate reduction in the stress of the web itself, while the stress in the steel member remained relatively constant. However, when the thickness of the bearing plate is increased from 60 to 80 mm, the stress of each part of the steel plate in the steel grid will be significantly reduced, and the maximum reduction can reach 48%. The improvement of concrete strength has little effect on the stress of the steel cell, and the C50 concrete strength grade used in the design is more reasonable.

Effect of grid section design on trawl size selectivity

Sorting grids are introduced in trawl fisheries to improve size selectivity and reduce the variability of results obtained with sorting devices constructed of netting e.g., codends. Grids are rigid or semi-rigid structures where the bar spacing defines the sizes of fish that can pass through. However, for size selection to occur, fish need to be oriented towards the grid in specific ways, which may depend on the netting construction where the grid is installed. In the Barents Sea gadoid trawl fishery, fishermen are allowed to use different netting configurations within the same type of grid, but it is unclear to which degree the performance of sorting grids depends on the construction characteristics of the netting section where they are installed. This study compares the size selective properties of a steel grid mounted in three different netting section configurations: 2-panel section, 4-panel section, and 4-panel section with a modified lifting panel. Overall, the results of the study demonstrate that the 2-panel configuration performs better than the two 4-panel configurations tested. The differences were smaller when the 2-panel and the 4-panel section with a modified lifting panel were compared. Specifically, the grid contact probability for haddock with the 2-panel configuration was 0.92 (0.90 – 0.95) and significantly higher than for the 4-panel configuration, which was estimated to be 0.82 (0.77 – 0.89). For cod, the grid contact probability between the different configurations did not vary more than 6% and the differences were not significant. The 4-panel configuration led to significantly higher retention of cod between 40 to 60 cm and haddock between 20 and 54 cm than the 2-panel configuration. The results also show that despite having been assumed to provide constant size selectivity, the performance of sorting grids is sensitive to relatively small design changes in the section where they are mounted.

Experimental and numerical investigation of the prefabricated steel–concrete open-web composite floor with embedded chords

To reduce the height and improve the installation efficiency of novel prefabricated steel-concrete open-web composite floor (SOF), a developed SOF was proposed. A full-scale (9.0 m × 9.0 m) laboratory test and detailed parametric finite element (FE) analysis were conducted to explore the load-bearing capacity, typical failure modes, load-displacement relationship, and strain variations at key locations of the structure. The experimental findings indicated that the concrete slab and upper chord exhibited good composite behavior, and no interfacial failure was observed between the concrete slab and the T-section. The joint diaphragm welds failed in tension due to insufficient capacity of the bottom chords, while web members continued to transfer axial tension, resulting in local tearing failures outside the plane. Further finite element analysis illustrated the damage evolution of the concrete slab and steel grids. Moreover, the mechanical properties of the structure were found to be relatively insensitive to the changes in geometric parameters across the different locations. The conclusions drawn from this study can be utilized as reference for the design and analysis of spatial composite slab structures.

Debonding sawtooth analytical model and FE implementation with in-house experimental validation for SRG-strengthened joints subjected to direct shear

A novel and simple analytical debonding model for Steel Reinforce Grout (SRG)-strengthened specimens subjected to direct shear tests is proposed. All the nonlinearity is lumped at the interface between reinforcement chords and mortar, the substrate is assumed perfectly glued to mortar, infinitely stiff and resistant and the steel grid is considered linear elastic. The non-linear interface tangential stress-slip relationship is assumed discontinuous and multi-linear and constituted by four phases, three elastic with progressively reduced stiffness and the last perfectly plastic. The assumption of a non-vanishing residual tangential strength is paramount to reproduce the typical pseudo-linear hardening observed experimentally in the global force-displacement curves when the debonding frontier is triggered starting from the loaded edge. Under such hypotheses, the second order differential field equation describing the slippage of the reinforcement on the support admits closed form solutions, which are suitably derived. An implementation into a standard Finite Element (FE) commercial code is also proposed, which relies in a discretization of the reinforcement through three cutoff bars (one ductile and two brittle) disposed in-parallel, elastic elements for the steel grid and rigid beams used as transversal connections. The reliability of the sawtooth and the FE models is assessed by means of a thorough comparison with experimental data obtained by the authors for this purpose testing five replicates of a concrete specimen strengthen with a SRG and subjected to a standard shear test.