بحوث سكوبس — يسار أمير علي

Reinforced concrete deep beams are a vital member of infrastructures such as bridges, shear walls, and foundation pile caps. Thousands of dollars and human lives are seriously threatened due to shear failure, which have developed in deep beams containing web openings. This paper investigates numerically the overall behavior of simply supported concrete deep beams reinforced with carbon fiber-reinforced polymer (CFRP) sheets through forty specimens grouped in four groups. The numerical analysis results agreed well with the experimental results in the literature, particularly the visual failure initiation with a failure load difference of nearly 7%. Finite element analyses indicated that the presence of an opening with considerable width reduced the failure load by about 71% compared to the corresponding solid specimens. In addition, the reinforced concrete deep beam samples started to behave differently when the (b/h) ratio increased more than (2.0). The findings showed that the compression stress strut pathway had been disrupted by the web opening leading to stress redistribution, and the structure will behave as two separate members. Thus, the upper web-opening part sustained the most stress, while the part under the web-opening did not show any stress concentration. The numerical stress distribution results showed that the attributed reason is that rebars and openings helped redirect the stresses to the compression strut. Using CFRP sheets with a width of more than 160 mm significantly improved the reinforced concrete deep beam with web-opening due to the increasing confinement to the upper part of the reinforced concrete deep beams with the opening. © 2022 by the authors.

This study investigates the overall behavior and performance of R.C. beams with CFRP plates for improving the infrastructure buildings performance. The parameters studied include different widths and thickness of fiber reinforced polymer plates along the beams tension face. For this analysis, a computer program (ABAQUS CAE.18) is used. To achieve the aim, two sets of beams have been analyzed. The first group consists of five specimens strengthened with CFRP plates of thickness 1.2 mm and width (25, 50, 75, 100 and 140) mm in flexure, the second group of beams also consist of five specimens strengthened with CFRP plates similar to the first group but with thickness of 2.4 mm and the control beam is without CFRP. A variety of CFRP width and thickness applications were tested to determine the ultimate strength of the beam specimens. A comparison is made between the experimental results from previous study done by (K. Shadhan) and the numerical model. The comparison indicates that the results of the numerical modeling were in good agreement with the experimental results (1.7% difference in ultimate strength for the specimen without CFRP strengthening and 1.6% difference for the specimen strengthened with CFRP plate of thickness 1.2 and width 100mm). Moreover, it can be noticed that the strengthening with CFRP plate with thickness of 1.2mm, the ultimate strength increases with the increase of the plate width and the increment reach 45% when plate width 75mm compared with specimen without CFRP. But, the ultimate strength decrease when CFRP plate width increased to 140mm (3.6% compared with specimen strengthened with 75mm CFRP plate). The strengthening with CFRP plates of 2.4 mm thick increases the ultimate strength more than when compared to beams reinforced with 1.2 mm thick CFRP plates of the same width (7.2%, 0.3%, 0.7%, 0.6%, 1.1%) for widths (25, 50, 75, 100, 140) mm, respectively. © 2023 Author(s).

In dense-graded pavements, which are used for composing and recomposing roads in the paving industry around the world, failures occur due to increasing traffic loads and the rising runoff of water caused by storms or floods, or any other reason. Therefore, this kind of issue can be treated by adopting a permeable pavement system such as the permeable interlocking concrete pavement (PICP) to manage the runoff of water and tolerate the increasing loads of traffic efficiently. In this study, a laboratory apparatus has been designed and fabricated as an artificial rainfall simulator to investigate the behavior of different surface concrete block patterns under different rainfall intensities. Measuring the levels of runoff and the volume of infiltrated water are the fundamental factors in creating an essential comparison between the elected surface patterns. In this study, stretcher bond, 90º herringbone, and 45° herringbone patterns are chosen with (5 mm and 10 mm) joint spacing between the concrete blocks. All three surface block patterns are tested in terms of four longitudinal slopes (0%, 2.5%, 5%, and 7.5%) and three side slopes (0%, 2.5%, and 5%) under three rainfall intensities (25 l/min, 50 l/min, and 75 l/min). Based on the results, the stretcher bond pattern showed superior results to other bonds because it reduces surface runoff and spreads the water evenly under the permeable concrete block roadway. The 90° herringbone and 45° herringbone patterns, on the other hand, are the best for increasing the durability of roads. © 2022 The Authors

The present study tackles the problem of forced vibration of imperfect axially functionally graded shell structure with truncated conical geometry. The linear and nonlinear large-deflection of the structure are considered in the mathematical formulation using von-Kármán models. Modified coupled stress method and principle of minimum virtual work are employed in the modeling to obtain the final governing equations. In addition, formulations of classical elasticity theory are also presented. Different functions, including the linear, convex, and exponential cross-section shapes, are considered in the grading material modeling along the thickness direction. The grading properties of the material are a direct result of the porosity change in the thickness direction. Vibration responses of the structure are calculated using the semi-analytical method of a couple of homotopy perturbation methods (HPM) and the generalized differential quadrature method (GDQM). Contradicting effects of small-scale, porosity, and volume fraction parameters on the nonlinear amplitude, frequency ratio, dynamic deflection, resonance frequency, and natural frequency are observed for shell structure under various boundary conditions. Copyright © 2022 Techno-Press, Ltd.

Using the ABAQUS software, this article presents a numerical investigation on the effects of various stud distributions on the behavior of composite beams. A total of 24 continuous 2-span composite beam samples with a span length of 1 m were examined (concrete slab at the top and steel I-section at the bottom). The concrete slab used is made of a reactive powder concrete with a compressive strength of 100.29 MPa. The total depth of each sample was 0.220 m. The samples were separated into four groups. The first group involved 6 specimens with shear connectors distributed into 2 rows with different distances (65, 85, 105, 150, 200, and 250 mm). The second group had the same spacing of shear connectors as the first group except that the shear connectors were distributed with one row along the longitudinal axis. The third group consisted of six specimens with single and double shear connectors distributed along the longitudinal axis. The fourth group included six specimens with one row of shear connectors arranged in a staggered distribution along the longitudinal axis. Results show that the optimum spacing was 105 mm in all groups and the deflection in group four fluctuated up and down due to the non-symmetrical distribution of the shear connectors. © 2022 Yasar Ameer Ali et al., published by De Gruyter.

Geotextile reinforcement techniques have been widely used in paving works around the world and have proven to be effective in improving pavement performance. This study has focused on using different positions and numbers of geotextile reinforcement sheets between the layers of flexible pavement for rutting reduction. Fitting depth was measured in the field at seven constructed sections of the pavement of the road model. Each section has been strengthened with different reinforcement approaches. All road sections were subjected to a maximum load repetition of 10,000 cycles. The results indicate that using three layers of geotextile beneath each course of the designed road pavement sections (surface, binder, and base) reduced rutting by 96%. Traffic benefit ratio (TBR) has been employed in this study to reveal the behavior of geotextile reinforcement in increasing the service life of the road. TBR values are the load cycling ratio between the reinforced and unreinforced section for the exact recorded rut depth, it has been found to be minimally equal to 4 for the case of using one layer of reinforcement at interface I, and that value keeps growing up for other reinforcement cases. © 2022 Abdul Hadi Meteab AL Sa'adi et al., published by De Gruyter.

The behavior of hollow-core columns composed of reactive powder concrete (RPC) contained by a circular carbon fiber reinforced polymer (CFRP) tube is investigated numerically in this work. This research used circular hollow core column samples with an outside diameter of 20.6 cm, an interior diameter of 9cm, and a height of 80cm. These examples have been created utilizing 116 MPa reactive powder concrete. Nine groupings of specimens were created. A control set of nine unconfined hollow columns with stirrups strengthened by 12mm longitudinal bars (HCRPC). Groups two through five have been produced up of RPC hollow column specimens with similar reinforcement but were externally confined with CFRP of 0.131, 0.262, 1.2, and 2.4mm thick (These thicknesses are commercially available (0.131 for CFRP one layer sheet, 0.262 for two layers of CFRP sheet; 1.2 for one layer of CFRP plate. And 2.4 for two-layer of CFRP plate) respectively, placed at mid-length of the columns. Sets six to nine, on the other hand, are identical to the previous sets, but the CFRP restriction has been put at both columns' ends. Axial load thru the column center and uniaxial loading with 2.5 and 5 cm eccentricities from the center were applied to all columns. According to the findings, CFRP confinement boosted the strength of HCRPC columns marginally. Also, column samples confined at mid-height with CFRP wrapping achieved a higher ultimate strength than those confined at both ends. © 2022 The Authors.

This paper presents a comparison designed to manipulate performance characteristics of ten reinforced concrete beams with and without openings under a single monotonic maximum stress at mid-span, depending on the configuration and size of the openings, using the ABAQUS/CAE finite element approach package. The cross-section, arrangement, and opening sizes of all the beams were identical to those of the test beams. The goal of the experimental comparison was to check that all simulation processes were proper and adequate. The numerical analysis results showed that in terms of the failure load, there was a 94 percent agreement between experimentally tested and numerical analysis results. In addition, it was shown that concentrated shear stresses at the corners of the openings causing the failure of the posts between the openings. The numerical study revealed that the influence of increasing main longitudinal steel reinforcement by 28% and 44% more efficient to enhance the ultimate load capacity by rates of 7.61% and 9.61%, respectively, compared to increasing the compressive strength of the beams by 24 %, which led to increasing the ultimate load capacity by 3.72%. Therefore, From the standpoint of difficulty and timesaving, the finite element approach is a very dependable technique for investigating the nonlinear behavior of beams with many apertures. © The Author 2022. This work is licensed under a Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) that allows others to share and adapt the material for any purpose (even commercially), in any medium with an acknowledgement of the work's authorship and initial publication in this journal.

In this study, a sustainable filler made from papyrus fiber ash (PFA) is used as a partial cement replacement in hot mix asphalt mixtures (HMA). The replacement levels used are 0, 5, 10, and 15% by weight of ordinary Portland cement. The hot mix asphalt samples were subjected to Marshal volumetric properties (stability, flow, and air voids) and service tests (tensile strength ratio test and immersion compression test) to predict the influence of the used filler modifier on the moisture sensitivity of blended HMA. Best results have been achieved by using 10% of PFA, whereas all the prepared samples with the mentioned percentage of the filler modifier showed a lower sensitivity to moisture in comparison with the control samples, which contained 0% of PFA. The used technique proved to be very efficient in keeping the pavement safe from deformation caused by moisture. At the same time, using sustainable filler materials proved to be an environmentally eco-friendly method. © 2022 Tameem Mohammed Hashim et al., published by De Gruyter.

This paper presents a numerical investigation for the behavior of simply supported T-section deep beams, which strengthened with Carbon Fiber Reinforced Polymer (CFRP) sheets. The used specimens were (1.8 m length), (450 mm width and 100 mm depth) flange dimensions, and (180 mm width and 360 mm depth) web dimensions. The specimens were divided into four groups. Mainly, the difference between specimens in each group is in the main reinforcement details. The control group consisted of six beams non-strengthen with CFRP, the other groups were similar to the control group but externally strengthened with CFRP sheets, which were (0.131 mm) thickness. In detail, the second group was strengthened with CFRP sheet at the bottom surface of the web. The third group was strengthened horizontally with CFRP sheets at both sides of the specimen's web. The last group was strengthened with three sheets of CFRP; one at the bottom face of the web and the others at the web sides. The results show that using CFRP at the bottom slightly increased the ultimate strength and changed the failure mode from flexural to shear. Using CFRP at the sides significantly increased both flexural and shear strength, while using CFRP at the sides and bottom of the web did not significantly enhance the ultimate strength in comparison with using CFRP at the sides only. © 2020 Trans Tech Publications Ltd, Switzerland.