Date palm fiber (DPF) has been reported to have many advantages when used in concrete, however, its major disadvantage is that it causes a reduction in compressive strength. In this research, powdered activated carbon (PAC) was added to cement in the DPF-reinforced concrete (DPFRC) to lessen the loss in strength. PAC has not been properly utilized as an additive in fiber reinforced concrete even though it has been reported to enhance the properties of cementitious composites. Response surface methodology (RSM) has also been utilized for experimental design, model development, results analysis, and optimization. The variables were DPF and PAC as additions each at proportions of 0%, 1%, 2%, and 3% by weight of cement. Slump, fresh density, mechanical strengths, and water absorption were the responses that were considered. From the results, both DPF and PAC decreased the workability of the concrete. DPF addition improved the splitting tensile and flexural strengths and reduced the compressive strength, and up to 2 wt% PAC addition enhanced the concrete’s strength and lowered the water absorption. The proposed models using RSM were extremely significant and have excellent predictive power for the concrete’s aforementioned properties. Each of the models was further validated experimentally and was found to have an average error of less than 5.5%. According to the results of the optimization, the optimal mix of 0.93 wt% DPF and 0.37 wt% PAC as cement additives resulted in the best properties of the DPFRC in terms of workability, strength, and water absorption. The optimization’s outcome received a 91% desirability rating. The addition of 1% PAC increased the 28-day compressive strength of the DPFRC containing 0%, 1% and 2% DPF by 9.67%, 11.13% and 5.5% respectively. Similarly, 1% PAC addition enhanced the 28-day split tensile strength of the DPFRC containing 0%, 1% and 2% by 8.54%, 11.08% and 19.3% respectively. Likewise, the 28-day flexural strength of DPFRC containing 0%, 1%, 2% and 3% improved by 8.3%, 11.15%, 18.7% and 6.73% respectively with the addition of 1% PAC. Lastly, 1% PAC addition led to a reduction in the water absorption of DPFRC containing 0% and 1% DPF by 17.93% and 12.2% respectively.

Date palm fiber (DPF) is one of the abundant solid waste materials in the agriculture sector in Saudi Arabia, and it is gaining great attraction due to its advantages compared to synthetic and other natural fibers. For proper utilization of DPF in cementitious composites, its performance under high temperatures needs to be understood. This is because DPF is a cellulose-based agricultural fiber material and is expected to degrade when subjected to high temperatures. This will cause a significant loss in strength and structural integrity of the composites. The use of Pozzolanic materials has been reported to reduce the loss in mechanical properties of cementitious composites under high temperatures. With powdered activated carbon (PAC) being a low-cost material compared to other Pozzolanic materials, this study utilized PAC as an additive to the DPF-reinforced concrete to mitigate its loss in mechanical strength when exposed to elevated temperature. The experiment was designed using response surface methodology (RSM), which was used to construct mathematical models for estimating the strengths of the concrete exposed to high temperatures. The DPF was added at proportions of 1%, 2%, and 3% by weight of cement. Similarly, the PAC was added at 1%, 2%, and 3% by weight of cement to the concrete. The concrete was subjected to elevated temperatures of 300 °C, 600 °C, and 900 °C for a 2 h exposure period. The degradation of the concrete in terms of mass loss and the compressive strength of the concrete after heating were measured. DPF in the concrete led to an escalation in weight loss and reduction in strength, which was more pronounced at a temperature of 600 °C and above. The addition of PAC resulted in an enhancement in the strengths of the concrete containing up to 2% DPF at 300 °C, while at 600 °C the improvement was minimal. The models developed for predicting the mass loss and strengths of the DPF-reinforced concrete under high temperatures were statistically significant with a high correlation degree. Based on the optimization results, DPF-reinforced concrete produced with 1% DPF, and 2.27% PAC as additives and subjected to a temperature of 300 °C for 2 h yielded the lowest mass loss of 2.05%, highest residual compressive strength and relative strength of 45.85 MPa and 106.7% respectively.

Steel I-beams may be subject to deviation from their normal path towards the lateral direction due to obstacles along their axis line. This deviation in the lateral direction, i.e., the out-of-plane distance, affects the behavior of the steel beams and may reduce their ultimate capacity. To obtain this effect, finite element modeling (FEM) was used to model these beams with and without an out-of-plane distance at the mid-span beam length with several different variables. These variables were the out-of-plane distance, cross-section dimensions, beam length, and steel yield stress. The reliability of using FEM simulation was confirmed by comparing the experimental test results of 25 available steel beams in previous studies. The results indicate the high accuracy of the simulation of this beam in terms of ultimate capacity, structural behavior, and deformation patterns. After verifying the results, 116 broad-flange I-beam (BFIB) steel beams with different out-of-plane distances were modeled. The results showed that using an out-of-plane distance equal to the flange width of the BFIB-300 cross-section caused a 60% decrease in the ultimate capacity. The reduction ratios in the ultimate moment capacity in out-of-plane steel beams were directly proportional to the out-of-plane distance, cross-sectional dimensions, and steel yield stress, while the beam length had no effect. Failure in beams containing an out-of-plane distance occurs as a result of a global buckling in the upper flange, which contains tensile stresses at the outer edge and compressive stresses at the inner edge, with stress concentration occurring at the point of contact of the out-of-plane part with the main beam. The prediction results of the design codes were compared with the results of experimental tests and the FEM analysis of the beams with and without out-of-plane distances. For all the beams with out-of-plane distances, all the design codes were unable to predict this ultimate capacity.

Three-dimensional finite-element (FE) simulations were developed to assess the flexural response of ultra-high-strength concrete (UHSC) beams reinforced with basalt-FRP (BFRP) bars and with BFRP–steel hybrids. The models were calibrated against published tests and reproduced midspan force–deflection curves, reinforcement strains, and crack development with good fidelity. A parametric study examined (i) the BFRP reinforcement ratio relative to a balanced level and (ii) the BFRP-to-steel area ratio in hybrid sections. Results show that increasing the BFRP ratio raises ultimate flexural capacity but reduces deformability and energy dissipation. Hybrid reinforcement recovers inelastic reserve while preserving the durability advantages of FRP, yielding a more favorable balance between strength and serviceability. A yield-anchored modified ductility index tailored for hybrid sections is formulated to quantify post-yield rotational capacity. The findings provide design guidance for proportioning UHSC beams in conventional and aggressive environments: BFRP reinforcement ratios of ρ_f/ρ_fb ≥ 1.4 are suitable where strength and durability dominate, whereas hybrid layouts are recommended when controlled deflection and ductility are also required.

Fiber-reinforced polymer (FRP) shear strengthening is generally selected on the basis of structural capacity, whereas the efficiency with which installed material contributes to shear resistance has received little quantitative attention. This study develops a literature-based material-efficiency framework from a database of 359 published tests compiled from 43 experimental programs covering carbon, glass, aramid, basalt, and PET-FRP systems. Material efficiency (ME) was defined as the experimentally attributed FRP shear contribution per unit mass of installed composite sheet. ME varied approximately 30-fold. Median ME was 303 kN·m·kg⁻¹ for CFRP and 38 kN·m·kg⁻¹ for GFRP, giving a CFRP:GFRP median-efficiency ratio of 8.1 (program-clustered 95% CI: 3.8–18.3; 2.8–21.3 when thickness-convention and density uncertainty were also propagated). This observational, database-level ratio, which is an association rather than a causal material effect, was translated into a sheet-level cradle-to-gate greenhouse-gas break-even screening criterion. A response-surface model based on XGBoost achieved random ten-fold out-of-fold R² = 0.802, decreasing to 0.526 under program-grouped validation and 0.394 under leave-one-program-out validation; most of this loss reflected program-level offsets. Member geometry and transverse reinforcement carried greater predictive importance for the attributed FRP contribution than FRP-sheet properties under both random and program-grouped validation. Material efficiency generally decreased with increasing installed sheet rigidity, consistent with diminishing structural returns from additional FRP material. The framework compares code-compliant alternatives that satisfy the required FRP shear contribution, using material efficiency to identify lower-material-demand solutions before project-specific environmental and economic evaluation.