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This paper presents an experimental investigation on the behavior and strength of reinforced concrete slabs with lap splice of tension reinforcement using headed bars. Nine simply supported reinforced concrete one-way slabs were tested to study the effect of lap splices length, confinement at the splice zone, debonding of bars in the splice zone, and applying repeated gradually increasing cyclic loading. It was concluded that implementation of lap splice length as stated by ACI 318-14 for headed bars, but without adding confinement in the splice zone, and using cut-off ratio equal to 100%, led to brittle failure of the slab and the ductility was reduced. When the tested slabs were provided with confinement in the splice zone, the strength of slabs was improved and ductility of these slabs was remarkably increased. Additionally, the integrity of the lap joint was preserved when subjected to repeated gradually increasing cyclic loading. [ABSTRACT FROM AUTHOR]

Superstructure loads are transmitted to the underlying soil strata through a suitably designed foundation. Therefore, the foundation of a structure is considered the most crucial structural element in a building. The foundation may be classified into two main categories, shallow and deep foundations. Shallow foundation comprises isolated column footings, combined footings and reinforced concrete mat. The design of isolated column footing is accomplished through the application of geotechnical and structural analysis concepts. So that, the input research into isolated column footings comes from two different disciplines, geotechnical and structural. This may be one of the main causes that attributed to the limited research input to the subject. Therefore, the structural design of isolated column footings is based on empirical rules and the calculations of bending moments (BM) and shearing forces (SF) induced in a footing are based on the rules of beam theory, which is questionable. On the other hand, punching theory was developed on relatively thin floor slab, even though the theory is implemented for the calculation of punching shear in relatively thick footings. Also experimental research on isolated column footings is scarce, due to the difficulties involved in the setup of the laboratory models and the cost of experiments. The work presented in this article deals with the correlation between failure loads predicted by different code provisions, ECP203-11, ACI318-08, BS 8110.1-1997 and EC2-2004, of isolated column footings, and the corresponding measured values. The study showed that shear span to depth ratio of a footing and distributions of contact stress at footing–soil interface are key factors in the structural design of the footing. ECP203-11, ACI318-08, and EC2-2004 code provisions, underestimate the structural failure loads of isolated column footings, while BS 8110.1-1997 overpredicts the failure loads of isolated column footings, if punching provisions at perimeter of column are pulled out from the code. [ABSTRACT FROM AUTHOR]

[Display omitted] • TiO 2 doped with Zr4+ were spin coated on glass substrate. • Amorphization of TiO 2 due to Zr-doping decreases band gap. • A natase crystallites size decrease with Zr-doping. • Zr-doping lower electron–hole recombination of TiO 2. Dense thin films of TiO 2 and TiO 2 doped with Zr4+ were spin coated on glass substrate and annealed at 450 °C. The optical characteristics and crystalline structure were studied using UV–vis, PL, XRD, and SEM. X-ray investigation proved that an anatase phase was formed in all Zr-doped samples (0, 0.5, 1, 5, and 10 %). Zr-doping changes the band gap energy from Eg = 3.48 eV (undoped) to 3.57 eV (1 % doping), along with the large size of Zr4+ results in slight lattice enlargement. Increasing Zr-doping beyond 1.0 % is associated with decreasing the band gap due to amorphization of TiO 2. The anatase crystallites growth is stalled with increasing doping; from 23.5 nm to 10.43 nm and micro-strain increases with increasing doping concentration. The changes in optical properties, crystal growth and structure properties are due to lattice strain created by the collective effect of Zr-doping and reduction in crystallite size. Zr-doped TiO 2 nanoparticles exhibited typical photoluminescence (PL) matching to the visible spectrum region when excited at 275 nm. The produced thin films had a lower rate of electron–hole recombination than TiO 2 that was not doped. [ABSTRACT FROM AUTHOR]

• Synthesis of Co 3 O 4 @CeO 2 by surfactant-based sol–gel/ calcination technique. • Co 3 O 4 addition can effectively improve the physicochemical, optical, and photocatalytic properties. • Complete ciprofloxacin photodegradation achieved in 30 min over Co 3 O 4 @CeO 2. • The degradation rate of 15% Co 3 O 4 @CeO 2 was 2 times higher than pristine CeO 2. • Co 3 O 4 @CeO 2 can be recycled five times without loss in its activity. : The widespread dispersal of antibiotic waste in freshwater has accelerated the water contamination that impacts the ecosystem. Moreover, different studies have discussed the expected green mineralization of such contaminants. : Herein, a unique Co 3 O 4 @CeO 2 nanocomposite was developed by incorporating different doses (5–20 wt%) of Co 3 O 4 nanoparticles (NPs) using a surfactant-based sol–gel/ calcination technique. The photocatalytic activity of Co 3 O 4 @CeO 2 nanocomposites was estimated in the degradation of ciprofloxacin (CIP) antibiotic under visible exposure. : Optimizing the Co 3 O 4 mass yields a bandgap semiconductor of 2.66 eV with a wide visible light. The 15% Co 3 O 4 @CeO 2 nanocomposite displayed the best CIP destruction performance after 45 min, with 2-fold greater activity than pure CeO 2 NPs. After 30 min of visible light illumination, 2.4 gL−1 dosage of 15% Co 3 O 4 @CeO 2 achieved complete CIP oxidation with a photoreaction rate of 0.12 min−1 and retained significant reusability after five runs. The explanation for the improved photocatalytic efficiency of the Co 3 O 4 @CeO 2 is postulated based on the effective segregation of photoinduced charge carriers via an S-scheme mechanism, where electron–hole pairs can easily move between CeO 2 and Co 3 O 4 because of their matched band locations. This research corroborates the use of nanoheterojunction oxides in rapidly removing antibiotic residues under visible light. [Display omitted] [ABSTRACT FROM AUTHOR]