Combining fiber with concrete mixes has become essential and its widespread use improves the strength of structural concrete elements. This research conducted an experiment into the structural performance of flat slabs with and without a square opening using four types of fiber (hooked-end, straight, corrugated steel fiber and polyolefin fiber) to gain a better understanding of how the variance of fiber type and shape effects the flexural behaviors of two-way slabs. The test program involved (a) testing the properties of hardened concrete, such as compressive properties, modulus of rupture and splitting tensile strength, and (b) testing the flexural behavior of two-way slabs. Ten slabs were divided into five pairs, including two specimens used as reference specimens (with and without openings), and eight other specimens with different types of fibers. Results revealed that the existing fiber in concrete improved the mechanical properties of hardened concrete mix, and the compressive strength test showed higher improvement in specimens with hooked and straight steel fiber. The flexural behavior of reinforced concrete slab was significantly enhanced, and the flexural strength capacity was especially improved for the slabs strengthened with hooked-end and corrugated steel fiber. Polyolefin fiber showed a slight enhancement of mechanical properties and good improvement in flexural capacity. Generally, the highest increments in compressive strength and modulus of rupture were 24.8%, 20% and 11%, and the ultimate load-carrying capacity of slabs was 39%, 13% and 19% for specimens with steel hooked, steel corrugated and polyolefin fibers, respectively, compared with control specimens.

It is very crucial to minimize the environmental impact that induced from the development of industry, by applying strict policies and innovate eco-friendly industries. Indeed, construction manufacture considered as one of the most industries that affect the environment, especially concrete production and usage in structural buildings. For instance, traditional concrete, which is consists of a high amount of cement, is contributed to the emission of CO2. Therefore, researchers seeking to develop a new technology of concrete by replacement some amount of cement by materials which are considered to become more friendly to the environment. Nowadays, this new technology is known as Green Concrete. The importance of using green concrete is not only to decrease the emission amounts of CO2 but also to replace cement by industrial waste. In this paper, a review has been presented to understand green concrete benefits and materials that may be used instead of cement and aggregate.

This study demonstrates the behavior of a flat slab experimentally and numerically with two different types of shear reinforcements. Ten slabs were cast and tested in the experimental part. The samples were divided into two groups; the first consists of steel fiber, and the second has no steel fiber. Two control samples were considered with only flexural reinforcement, while the other eight samples had two types of shear reinforcement; the first was rebar to form a Y-shape, while the other was a steel plate formed as a Y-type perfobond. Shear reinforcement is provided by employing radial and parallel shear reinforcement. The tested samples in the experimental part have been simulated numerically using the Abaqus/CAE program. As a result of the laboratory examination, it was determined that the addition of steel fibers increased the ultimate load by (7.4% to 20.58%) for models with steel fibers compared to models without steel fibers. It was determined that the presence of steel plates in the models increased their capacity by 2.4% for ultimate load and by (6% to 50%) for deflection compared to ultimate load and deflection in models with steel bars. In Abaqus, the models with steel fibers were found to be 12.7%-26.6% stronger than those without them.

This paper presents the influence of polyolefin fiber on the flexural and shear attitude on the flat slabs. Three slab sets (80 cm × 80 cm) were tested, each with a thickness of 10 cm. In the first set (S1), the effect of fiber content on the flexural behavior of the flat slab was considered. Therefore, four slab specimens were cast, one of which was considered as a control specimen with no fiber content, while the other three included fibers at 0.5, 1, and 1.5 percent of the total concrete volume. The second series of experiments studied the flexural behavior of flat slabs (S2) with an opening of 15 cm × 15 cm. The first specimen contained nil polyolefin, while the second included 1% polyolefin. In the third set (S3), consideration was taken for 0 and 1% of Polyolefin to realize the shear behavior of the flat slab. The increase in polyolefin fiber content from 0 to 1.5% (for slab set 1) will decrease the deflection from 4.5 mm to 2.3 mm, with an average of 3.58 mm, which is close to the deflection of a 1% polyolefin fiber specimen. Three dimensional models for the tested slabs were simulated numerically via ABAQUS software program. The ratio of the maximum deflection between the experimental and the numerical outcomes were varied with a range of 1.01 to 1.28, with an average of 1.14.

The structural behavior of Reinforced Concrete Haunched Beams (RCHBs) was investigated in this study. One prismatic control beam and fourteen Haunched Beams (HBs) were used in the experimental test and numerical analysis. The variables considered are Recycled Concrete Aggregate (RCA) ratio which is taken as 0, 30 %, and 60 %, opening shape (square and circular with the same area of 4560 mm2), and haunch angle (α) of 6.34° and 9.46°. The samples of dimensions (1750x200x300) mm were tested under a two-point load. The samples were simulated numerically using the Abaqus/CAE tool. The experimental outcomes show that using 30% RCA decreased the resistance by 8.24% - 26.45% compared with the control sample. While at 60% RCA, the resistance decreased by 16.35% - 34.71%. HBs with α=6.34° give a strength quite close to the control beam (PN) by 1.93%, while α=9.46° decreases the strength by 12.94% compared with PN. Compared with the solid beam, square holes in HBs provide a strength reduction range of 5.83% - 18.79% for α=6.34° and α=9.46°, respectively. The beams with circular apertures have a resistance decrease of about 3.43% - 14.70%, which corresponds to α=6.34° and α=9.46°. The numerical findings were 8.41% of the experimental data.