Flexural toughness and ductility characteristics of polyvinyl-alcohol fibre reinforced concrete (PVA-FRC)

This paper presents the results of an experimental study investigating the effect of un-coated polyvinyl alcohol (PVA) fibres on the properties of hardened concrete. PVA fibre of varying lengths, 6 and 12 mm and aspect ratio (l/d) of 430 and 860, respectively, was utilised in different volume fractions of 0.125%, 0.25%, and 0.5%. In addition, 30% fly ash was also used as partial replacement of Portland cement in all fibre reinforced concrete (FRC) mixes. Uniaxial compression, splitting tensile, modulus of rupture (MOR) and modulus of elasticity (MOE) tests were performed following the Australian Standards to evaluate the mechanical properties of PVA-FRCs. Fracture test is also conducted in accordance with European Standard in order to evaluate the residual flexural tensile strength and limit of proportionality of PVA-FRCs. Furthermore, the structural properties of reinforced concrete (RC) beams incorporating PVA fibres are investigated for their load-deflection behaviour using 4-point loading. Flexural toughness of the test specimens and peak load deflection were measured and discussed indicating to what extent the un-coated PVA fibre can enhance the brittle-like behaviour of concrete. Results show that adding PVA fibres to the mix generally improves the mechanical properties of concrete. Regarding the strength, the optimum fibre content goes to 0.25% for both fibre lengths and in the case of toughness and ultimate deflection 0.5% shows the highest values. An increase of 30% in ductility is noted for the RC beam incorporating 0.5% by volume fraction of 12 mm PVA fibre

Control of wind-induced motion of tall buildings using smart façade systems

The development of non-load bearing curtain walling technology around the turn of the 20th centre along with the effects to reduce the energy consumption of the building and dependence on artificial lightening, as well as the development of high performance glass and efficient building systems has seen ar-chitectural trends to move toward maximising glass surface areas in order to optimise natural daylight. This present study shows the potential offaçade systems potential to become an energy absorber of wind-induced vibrations. The façade has been rarely considered or designed as a potential wind-induced vibration absorber for tall buildings in the past. In this paper the potential of utilizing a moveable exterior façade in a double-skin façade is investigated and shown that with optimal choices of materials for stiffness and damping of brackets connecting the two skins, a substantial portion of wind-induced vibration energy can be dissipated which leads to avoiding expensive lateral stiffening systems and/or space consuming large damper systems such as tuned mass or liquid dampers. The work has demonstrated that up to 50% of response caused by winds can be absorbed by a smart and efficient façade design, including purely passive systems with constant stiffness and damping or better, by a smart a system possessing variable stiffness for different phases of façade move-ment

Static mechanical properties of polyvinyl alcohol fibre reinforced concrete (PVA-FRC)

This investigation assessed the performance of polyvinyl alcohol (PVA) fibres of 6 mm and 12 mm length in concrete. Based on total concrete volume, four fibre fractions (0.125, 0.25, 0.375 and 0.5%) were evaluated for their effect on fresh and hardened properties of PVA fibre reinforced concretes (PVA-FRCs). Fly ash was also used as partial replacement of Portland cement in all the mixes. By carrying out a comprehensive set of experiments (compressive strength, splitting tensile strength, modulus of elasticity, modulus of rupture and residual flexural strength), it was observed that PVA fibre significantly enhances the static mechanical properties of concrete as well as improving its post-peak response and ductile behaviour

Control Of Wind-Induced Motion Of Tall Buildings Using Smart Facade Systems

The development of non-load bearing curtain walling technology around the turn of the 20th centre along with an effort to reduce the energy consumption of the building and dependence on artificial lightening, the development of high performance glass and efficient building system has seen architectural trends move toward maximising glass surface areas in order to optimise natural light. This presents an opportunity to also investigate the façade system potential to become a filter for wind-induced vibration. The façade has been rarely considered or designed as a potential windinduced vibration absorber for tall buildings. In this paper the potential of utilizing a moveable exterior façade in a double-skin façade system is investigated and shown that with optimal choices of materials for stiffness and damping of brackets connecting the two skins, a substantial portion of wind-induced vibration energy can be dissipated which leads to avoiding expensive lateral stiffening systems and/or space consuming large damper systems such as tuned mass or liquid dampers. The works have demonstrated that up to 50% of response caused by winds can be absorbed by a smart and efficient façade design, including purely passive systems with constant stiffness and damping or better, by a smart system possessing variable stiffness for different phases of façade movement

Analysis of heavy metals concentration in Kano herbal preparations for major disease conditions

The use of herbal medicines for treatment, management and prevention of different disease conditions has been as old as human history. These herbs usually contained some chemical substances which are considered as beneficial, while others were not. Study of the levels of some essential (Copper, Cadmium, Cobalt, Iron, Manganese, Nickel and zinc) and toxic (Cd and Pb) heavy metals content of herbal preparations sold in Kurmi market of Kano state, Nigeria was carried out. The aim of this study is to evaluate the levels of essential and toxic heavy metals in Kano herbal preparations used for commonly identified disease conditions. The samples were digested by wet digestion method with nitric acid and perchloric acids and analyzed using Flame Atomic Absorption Spectrometer (FAAS). The data obtained were statistically treated and the results presented as mean of three replicated. The range of mean concentrations of the essentials Cu, Co, Fe, Mn, Ni, Zn and toxic Cd, Pb heavy metals obtained were 4.94-10.03μg/g, 3.33-3.80μg/g, 163.04-350.95 μg/g, 57.57-65.05μg/g, 9.94-15.63μg/g,, 6.86-66.59 μg/g and 1.53-3.23μg/g, 3.75-35.24 μg/g respectively. The level of contamination of the herbal preparation with the toxic heavy metals indicated 100% of the samples analyzed contained cadmium above WHO permissible limits (0.3μg/g) specified for herbal medicine and 33% of the samples contained lead (Pb) above WHO permissible limits (10μg/g) specified for herbal medicine. The gross level of contamination of these herbal preparations with Pb and Cd metals could be associated to poor adherence to quality control requirements such as current/good manufacturing practice (CGMP) and effective surveillance/enforcement. There is need for commitment for immediate action by both the herbal medicine practitioners and the relevant stakeholders in order to avert impending health hazards due to the tendency of gradual accumulation of these toxic metals in the body system of the consumers of these herbal preparations in order to attain to safe and effective herbal medicine usage in Nigeria.Keywords: Disease conditions, Heavy metals, Herbal preparations, Kan

Location of the maximum scouring depth at the outlet of partially-blocked and non-blocked box culvert

Among various hydraulic structures, culvert is the most likely one which usually blocks by the debris that are carrying by flow during large flood events. The size of the structure and its location where a waterway crosses a road or railway increases the possibility of clogging. The blockage of culvert accelerates bed scouring at the outlet hence affects bed scouring profile. This leads to increase the risk of culvert collapsed and produce different kinds of damages to the society. The present study concerns the effect of upstream blockage on the scouring profile at the outlet of a box culvert. Therefore, the experimental program was designed to investigate the relationship between the scouring geometry and blockage ratio. The experimental tests were carried out under non-blocked and partially blocked conditions. The sediment material used in this study was uniform non-cohesive sand material. Results showed that the scouring bed profile is different in partially blocked condition when compared to the non-blocked condition. Additionally it was found that the maximum scouring depth in a partially blocked culvert occurred at a distance very close to the outlet of the box culvert. © 2014 Taylor & Francis Group, London

Significance of bedrock depth in dynamic soil-structure interaction analysis for moment resisting frames

In this study, a fifteen storey moment resisting building frame, resting on a shallow foundation, is selected in conjunction with two clayey soils with the shear wave velocities less than 600m/s, representing soil classes De and Ee, according to AS 1170.4. Different bedrock depths including 10m, 20m, and 30 m are employed in the numerical modelling using finite difference software FLAC 2D. Fully nonlinear dynamic analysis under the influence of different earthquake records is conducted, and the results of the three different cases are compared and discussed. The results indicate that the dynamic properties of the subsoil such as shear wave velocity as well as bedrock depth play significant roles in seismic response of the building frames under the influence of soil-structure interaction. As the bedrock depth increases, lateral deflections and inter-storey drifts of the structures increase. These effects can change the performance level of structures from life safe to near collapse or total collapse. Therefore, the conventional design procedure excluding SSI is not adequate enough to guarantee the structural safety for the building frames resting on soft soil deposits

Effects of soil-pile-structure interaction on seismic response of moment resisting buildings on soft soil

Dynamic response of structures sitting on soft soils is influenced by the soil properties, and the response is significantly different to the fixed base condition owing to the interaction between the ground and the structure, In order to study this effect, a fifteen storey moment resisting building frame, representing a conventional type of regular mid-rise building frame, resting ,on soil type Ee according to Australian Earthquake action code with the shear wave velocity equal to 150 mls is adopted. The numerical analysis using FLAC2D software is carried out for three different cases, namely: (1) fixed-base structure representing the situation excluding the soil-structure interaction (SSI); (2) structure supported by shallow foundation on soft soil; and (3) structure supported by pile foundation in soft soil. Benchmark earthquakes including the 1995 Kobe, the 1994 Northridge, the 1968 Hachinohe, and the 1940 EI Centro earthquakes are adopted. Results indicate that considering soil-structure interaction in both cases with shallow and pile fouudations is vital, and the conventional desigu procedure excluding soil-structure interaction is not adequate to guarantee the structural safety for the moment resisting buildings resting on the soft soil

Metal content determination of some sexual dysfunction medicine samples in northern Nigeria

Essential minerals are those that are necessary for normal physiological and biological functions of human body. They act as catalysts such that only trace amount are necessary for cellular function. The study analyzed nine (9) different sex-drive herbal preparations used in the North-western part of Nigeria for essential minerals using Atomic Absorption Spectrophotometric (AAS) method in order to ascertain relationship between sex-drive and the mineral content of these herbal medicines. The result obtained shows the range of the mean concentration of Fe, Cu, Mn, and Zn to be (231.13-440.64)µg/g, (7.74 - 25.93)µg/g, (14.09 - 59.66)µg/g and (6.86 -74.41)µg/g respectively. The presence of Fe, Cu and Zn indicated the potential role of these herbal preparations in alleviation of sexual dysfunction problems and serves as sex-drivers. The average concentration of Cu and Zn obtained in the samples were above the World Health Organization (WHO) and US Food and Drugs Administration (FDA) permissible limit in herbal drugs as Cu (20ppm) and Zn (50ppm). The consumers’ of these products need to be cautioned otherwise the tendency of overload which will further result to health hazard is certain.Keywords: Herbal medicine, Sex-drive, Essential mineral

Evaluation of efficacious activities of aqueous extract of Phyllanthus niruri against acetaminophen-induced hepatitis in rats

The efficacy of aqueous extract of Phyllanthus niruri against acetaminophen-induced hepatitis in rats was evaluated. The hepatic injury was induced with 200 mg/kg, p.o. of acetaminophen, which led to rise in serum levels of the biochemical parameters observed. These are the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) which were elevated by 22% compared to respective negative control. Treatment with the plant extract (500, 1000 and 2000 mg/kg, p.o.) lowered the biochemical parameters of the respective serum AST 31 to 38%, ALT 20 to 31%, Bilirubin -2 to 4%, protein 5 to 15%, cholesterol 0.2 to 0.5%, and albumin 5 to 12%. The histopathological results indicated that, the effect of the extracts on the condition of the liver as compared to the normal control ranges from mild to moderate. The biochemical variations were as a result of the different treatment involved in the study. The result therefore, shows lowering of the elevated parameters in the serum and possible reversal of hepatic cell damage with aqueous extract of Phyllanthus niruri. The trend of the study shows that, the longer the period of treatment at lower doses, the better the efficacy of the plant extract.Keywords: Phyllanthus niruri, hepatitis, acetaminophen, biochemical, histopathology, rat