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A thorough review was performed to outline the general procedures used for performing drop-weight testing on concrete beam members. Highlights of this review include the problems associated with early tests and the methods used to overcome them, which have now become standard practice. The findings of various types of concrete beams under low-velocity impact have also been examined. These include the impact behavior of conventionally reinforced, fiber-reinforced, and prestressed concrete beams. Next, a database of various concrete beam types has been carefully built for the development and discussion of observed trends. When applicable, comparison of the recorded drop-weight behavior of conventional reinforced concrete (RC) beams was aggregated to its ACI design capacity. Finally, empirical relations for both flexuraland shear-critical members are suggested, with applicability to the ACI design standard. Keywords: ACI design equation; drop-weight testing; fiber-reinforced concrete beams; prestressed concrete beams; reinforced concrete beams.

In the present study, a unified shear-strength model based on a compression zone failure mechanism was developed to predict the shear strengths of nonprestressed and prestressed concrete beams. In concrete beams damaged by flexural cracking, concrete shear resistance is mainly provided by the compression zone of intact concrete rather than the tension zone with flexural cracking. In this study, the principal stress failure criteria of concrete were used to derive the shear capacity of the compression zone, considering the effect of the compressive stress developed by flexural moment. To address the contribution of the tension zone, concrete residual tensile stresses acting across the web cracks were considered. The proposed method was applied to existing test specimens with a wide range of design parameters. The results showed that the predictions of the proposed method agreed with the test results of nonprestressed and prestressed concrete beams. A design example was provided to demonstrate the application of the proposed method to the actual design.

The aim of this research work is to investigate the efficiency of newly developed Natural Fiber Rope Reinforced Polymer (NFRRP) composites to enhance the shear strength of reinforced concrete (RC) beams. Two types of NFRRP composites were made using low-cost hemp and cotton fiber ropes. The effectiveness of this NFRRP confinement in increasing the shear, energy dissipation, and deformation capacities of concrete beams was studied. The effect of these natural fiber ropes with different configurations on beams was investigated. The responses of seven RC beams with different spacing arrangements of natural fiber ropes were evaluated in terms of shear enhancement, deflection, energy dissipation capacity, effect of strengthening configuration, rope types, and ultimate failure modes. The NFRRP composites exceptionally enhanced the load carrying abilities, energy dissipation, and deformation capabilities of RC beams as compared to the control beam. The ultimate load carrying capacities of natural hemp and cotton Fiber Rope Reinforced Polymer (FRRP) composite confined beams were found to be 63% and 56% higher than that of the control beam, respectively. Thus, the shear strengthening of RC beams using natural fiber ropes is found to be an effective technique. Finite Element Analysis was also carried out by using the Advanced Tool for Engineering Nonlinear Analysis (ATENA) software. The analysis results compare favorably with the tests’ results.

This research paper presents a numerical analysis of composite box steel-concrete beams with transverse intermediate to large openings, conducted using the ABAQUS program. The study focused on various parameters, including opening size, shape, location, shear span to effective depth ratio, compressive strength, and diameter of rebars, to understand their effects on the shear load capacity of the beams. The results demonstrated a strong agreement with experimental data, with a correlation ranging from 0.927 to 1.023. Key findings include Increasing the opening size from 90x90 mm to 110x110 mm and from 110x110 to 136x136 led to a 12.7% and 42.4% respectively decrease in shear load, Changing the shape of openings from square to circular decreased the shear load by 14.7% for 90 mm openings and 14.2% for 110 mm openings, while increased the shear load by 15.25% for 136 mm. Moving transverse openings closer to the loads by 126 mm reduced the shear load by 7.5% for 90x90 mm openings, 9.8% for 110x110 mm openings and 17.2% for 136×136 mm openings. The difference in shear load between the highest and lowest (a/d) ratios is 12.5% for 90×90 mm openings, 7.2% for 110×110 mm openings, and 0.8% for 136×136 mm openings. Beams with a compressive strength of 37.5 MPa showed higher shear loads compared to those with 30 MPa, with increases of slight change, and the shear load increased of slight change for beams with reinforcement (2ø25-2ø16) compared to those with (3ø16) for 90x90 mm openings, 110x110 mm and 136x136 mm openings.

One of the major advantages of using glass fiber-reinforced polymer bars as a replacement to the traditional steel-reinforced bars is its lightweight and high-resistant to corrosion. This research focuses on the performance of concrete beams partially/fully reinforced with glass fiber-reinforced polymer bars with 50% of GFRP bars were used to reinforce partially concrete beams at flexural zone. While 100% of GFRP bars were used to reinforce fully concrete beams at flexural and compression zones with different concrete compressive strength. This study reported the test results of 6 reinforced concrete beams with dimensions 150 × 200mm and a 1700-mm clear span length subjected to a four-point loading system. The tested beams were divided into three groups; the first one refers to the glass fiber-reinforced polymer bar effect. The second group is referring to the effect of concrete compressive strength, while the third group is referring to the effect of the GFRP bar volume ratio. Using longitudinal GFRP bars as a full or partial replacement of longitudinal steel bar reinforcement led to an increase in the failure load capacity and the average crack width, while a decrease in ductility was reported with a lower number of cracks. Increasing the concrete compressive strength is more compatible with GFRP bar reinforcement and enhanced the failure performance of beams compared with normal compressive strength concrete.

The use of combined reinforcement in the form of external S275 steel tape and A1000 high-strength rebar is generally interesting for research. The use of a package of reinforcement enables a better choice of a rational cross-section area of reinforcement by varying the rebar diameter or the width of the steel tape. In addition, an interesting issue for research is the limit strain values of reinforcement of different strength classes since they can differ significantly, which affects the operation of the structure as a whole. For structures with combined reinforcement, there is still the number of issues not studied yet: for example, the stages of inclusion in the work of reinforcement and the magnitude of forces perceived by particular type of the reinforcement, the process and reasons for the destruction of experimental samples, the feasibility of such reinforcement, and the effect of high-strength rebar on the strength and deformability of reinforced concrete structures. Given that the issue of combined reinforcement is not sufficiently studied, the main task of the study was to investigate the stress–strain state of reinforced concrete beams with combined reinforcement (high-strength A1000 steel bars in combination with external S275 steel tape) in more detail.

The dynamic behavior of three-layer composite beams, consisting of concrete slabs and steel beams, is influenced by the structural configuration of each layer as well as the shear connectors. The interlayer shear stiffness in three-layer composite beams governs their global dynamic behavior, while interlayer slippage-induced localized vibration effects represent a key limiting factor in practical applications. Based on the dynamic test results of steel–concrete double-layer composite beams, the feasibility of a finite element solid model for composite beams, which accounts for interlayer shear connectors and beam body characteristics, has been validated. Utilizing identical modeling parameters, an analytical model for the inherent vibration characteristics of three-layer steel–concrete composite beams has been developed. This study encompasses two types of composite beams: concrete–steel–concrete (CSC) and concrete–concrete–steel (CCS). Numerical simulations and theoretical analysis systematically investigated the effects of interface shear connector arrangements and structural geometric parameters on dynamic performance. Research indicates that the natural frequency of steel–concrete three-layer composite beams exhibits a distinct two-stage increasing trend with the enhancement in interlayer shear stiffness. For CSC-type simply supported composite beams, the fundamental vertical vibration frequency increases by 37.82% when achieving full shear connection at both interfaces compared to the unconnected state, while two-equal-span continuous beams show a 38.06% improvement. However, significant differences remain between the fully shear-connected state and theoretical rigid-bonding condition, with frequency discrepancies of 24.69% for simply supported beams and 24.07% for continuous beams. Notably, CCS-type simply supported beams display a 12.07% frequency increase with full concrete-to-concrete connection, exceeding even the theoretical rigid-bonding frequency value. Longitudinal connector arrangement non-uniformity significantly impacts dynamic characteristics, while the transverse arrangement has minimal influence. Among structural parameters, steel flange plate thickness has the most significant effect, followed by concrete slab width and thickness, with steel web thickness having the least impact. Based on the observation that the first-order vertical vibration frequency of three-layer composite beams exhibits a two-stage decreasing trend with an increase in the span-to-depth ratio, it is recommended that the span-to-depth ratio of three-layer steel–concrete composite beams should not be less than 10.

This study proposes a unified shear design provision for slender steel- and fiber-reinforced polymer (FRP)-reinforced concrete (RC) members. The proposed model is a modification of the ACI 318-19 model to include the axial stiffness of the longitudinal reinforcement by introducing a new modification term, [n.sub.c], representing the elastic modular ratio of the longitudinal reinforcement to the concrete. The new relation is [Please download the PDF to view the mathematical expression]. The unified shear model was assessed with five experimental data sets: FRP-RC beams without shear reinforcement (288 beams), steel-RC beams without shear reinforcement (759 beams), FRP-RC beams with shear reinforcement (56 beams), steel-RC beams with shear reinforcement (157 beams), and steel-RC beams with axial force (prestressed) but without shear reinforcement (209 beams). The unified shear model provided better performance than the ACI 318-19 and ACI CODE-440.11-22 provisions in terms of mean, coefficient of variation, standard deviation (SD), and absolute average error (AAE). The unified model also showed improved performance over a wider range of material properties. In addition, reliability analysis using Monte Carlo simulation indicated that the unified shear model provides a consistent satisfactory safety level with a reliability index between 3.5 and 4.0 for both steel- and FRP-RC members. The reliability index provided by the unified model is similar to the reliability index provided by the ACI 318-19 shear provision. In contrast, the ACI CODE-440.11-22 results in highly conservative estimates with a reliability index between 4.5 and 5.0. Keywords: ACI 440; axial stiffness; code evaluation; fiber-reinforced polymer (FRP)-reinforced concrete (RC) beams; fiber-reinforced polymer (FRP) reinforcement; reliability analysis; shear strength; steel-reinforced concrete beams; steel reinforcement.

Through the combination of two approaches to evaluating structure change, a structural model and an unstructured model, a constructed model has been proposed in this article that evaluates structural change through the expansion of a linear model following the Hooke’s Law principle. The study has relied on the pure compression model of a structure’s concrete beam with elastic modulus (E) and has added the coefficient of viscosity resistance (C) to suggest a new evaluation method. By defining the aggregation of values of both coefficients C and E through the experimental model, the input parameters are the amplitude values of the vibration spectra and the values of frequencies based on machine learning, through which Z EC values are generated. The Z EC values determine a regression plane accumulated from the aggregation of values for both C and E. The article has introduced the Z EC concept as a useful parameter for the assessment of the quality of concrete structures by the nonlinear model with the appearance of the coefficient C. The results show that the Z EC values have expressed the distribution validity according to the structure’s differing degrees of change. Depending on the texture type and the structure status, these Z EC values will form different shapes. By implementing the actual surveys from many bridges with two types of beam structures, prestressed concrete and conjugated concrete, the Z EC values show the same development trend. On the contrary, in the case of a change in mechanical structure, the Z EC values tend to increase. This evidence proves, in regard to the process of structural change, that the larger the changes in the structure, the more pronounced the distribution of Z EC values, and the wider the distribution range. This shows that the ratio of the damping coefficient C to the elastic modulus E will become increasingly unstable as the structure becomes weaker and weaker. In the future, the results from this study can be applied in the assessment of many types of actual structures.

The application of used glazed waste in concrete production can improve the performance of the structure of the building. Flexural and shear behavior and action of reinforced HollowGlass Concrete Beams (HGCB) and Solid Glass Concrete Beams (SGCB) made with glass waste under a two-point load are studied in this paper. In this work, 6 reinforced concrete solid and hollow beams were tested under a four-point bending test to evaluate and calculate the flexural behavior of SGCB and HGCB. For that purpose, Beams were prepared with 1000 mm length, 230 mm height, and 120 mm. All beams were divided into groups and named according to the space stirrups steel bar. The experimental work investigates five main variables which are: first: the comparison between SGCB and HGCB with the concrete beams made with glass waste (Glass Concrete Beam GCB), second: comparison between Solid Concrete Beams for Normal Concrete Beams (NCB), and GCB, three: comparison between Hollow Concrete Beams for NCB and GCB, four: the comparison between HGCB and HCB, last: the comparison between SGCB and SCB. The test results indicated that GCB was offered higher strength than NCB, but the load–slip behavior of all specimens is similar for both types of concretes, and the bond strength is not influenced by steel specimens. Furthermore, the results of this study indicated that the contribution of GCB to the load is indicated to be considerable. The results indicate that the hollow opening affected the ultimate load capacity and deflection of HGCB.