While continuous reinforced concrete deep beams with fixed and hinged support conditions are every so often found in structures, little research has focused on their performance. This, in part, can be attributed to the demanding nature of ensuring fixed supports in experimentally testing such members. Nonetheless, conducting numerical analysis in comparison with experimental study has been a typical technique for producing a reliable numerical model as an alternative to destructive tests. This paper is aimed at numerically investigating the impact of different support conditions in the performance of two-span continuous reinforced concrete deep beams. A numerical model of three experimentally tested beams with two exterior rollers and interior hinge support conditions was generated. Good comparison, with an acceptable variation between numerical and experimental results, was achieved by tuning a few parameters in the numerical model, including element type, mesh size, and material constitutive relations. The refined numerical model was used as an alternative to destructive tests to conduct a parametric study to further investigate the impact of different sets of support conditions in the performance of two-span continuous reinforced concrete deep beams. This study highlights the potentially serious consequences of the support conditions in the performance of such deep beams.

This paper aims to examine the nonlinear flexural behavior of continuous RC beam specimens strengthened with fabric-reinforced cementitious matrix (FRCM) composites through experimental testing and numerical modeling. A total of nine two-span RC beam specimens were constructed and tested. Test parameters included the type of FRCM (carbon (C-FRCM) and polyparaphenylene benzobisoxazole (PBO-FRCM), location of strengthening (sagging and hogging regions) and number of FRCM layers (two and four layers). Test results indicated that sagging strengthening resulted in a strength gain in the range of 17 to 29%, whereas hogging strengthening increased the load capacity by 9 to 17%. The use of C-FRCM resulted in a higher strength gain than that provided by PBO-FRCM composites. Specimens strengthened with PBO-FRCM exhibited, however, higher ductility and deformational capacity than those of their counterparts strengthened with C-FRCM. Doubling the number of FRCM layers resulted in no or insignificant increase in the load capacity but reduced the beam ductility. Specimens strengthened in the sagging regions exhibited moment redistribution ratios of 13 to 26% between the hogging and sagging regions. Insignificant moment redistribution was recorded for the specimens strengthened in the hogging region. Three-dimensional (3D) numerical simulation models, with and without an interfacial bond-slip law at the fabric–matrix interface, were developed. The inclusion of the bond-slip law in the modeling had an insignificant effect on predicted response. Although the models tended to underestimate the deflection, the predicted load capacities were within a 12% error band. Numerical findings were in agreement with those obtained from laboratory testing.

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Abstract. Alkali-activated polymer concrete (APC) can potentially reduce CO2 emissions associated to concrete production by 84%. The binder in APC herein was synthesized using a combined sodium silicate-sodium hydroxide solution (i.e., alkali activator), alumino-silicate rich precursor (fly ash) and slag. Light weight expanded clay and desert dune sand were used as aggregates. An overview of an experimental program was presented, which involved evaluation of fresh and mechanical properties of the produced APC and counterpart mortar (APM). Variables investigated were the fly ash to slag ratio and curing conditions. The curing regimes adopted herein included 24 hours of curing at ambient conditions, 30oC, and 60 o C. The experimental program was undertaken in two stages, of these the first stage involved physical and chemical testing of constituent materials and the second stage involved testing or produced APM/APC. Reported were the setting times, workability, compression strength, strength development, flexural strength, tensile splitting strength, and plastic shrinkage strains. Relationship between strength results were investigated and effectiveness of codified predictive equations was evaluated.

The use of precast inverted T-beams has been frequently used to minimize construction activities and installation time. However, shipping and placement of large invert T-beams can become challenging tasks due to their weight. Decreasing the web height of the beam can be effective in reducing the beam weight. This paper considers inverted T-beams with two overhangs, negative moment regions, and one span, a positive moment region. The examined parameters were the web height and skew angle of the inverted T-beams. To avoid high costs of testing beams and to save time, the application of numerical modeling is, hence, inevitable. A calibrated 3D nonlinear numerical model, using ATENA software, was further used to numerically investigate the effects of reducing the weight, by decreasing the web height and varying the skew angle of inverted T-beams on their structural performance. The outcomes of this study indicated that reducing the web height of the beam was an effective tool to reduce the weight without jeopardizing the strength of the beams. Increasing the skew angle of the inverted T-beam also decreased their ductility.