Vibration-Based Structural Health Monitoring: Theoretical Foundations and Experimental Validation on Reinforced Concrete Beams

Quick identification of damages in structures is of great importance to engineers. Among the various techniques available for the evaluation of reinforced concrete structural integrity, non-destructive tests method remain a viable one as its use can lead to speedy decisions that bring savings on repairs or replacement of damaged reinforced concrete structures. This research uses modal parameter-based non- destructive tests to assess damages in reinforced concrete beams under static load. Four-point static loadings were applied to the 3 RC beams to induce three damage scenarios. After each static loading, a dynamic test was performed to access the degree of stiffness degradation. Modal frequencies and mode shapes obtained depicts clearly the stiffness degradations of the beams as the severity of damages on the beams became more pronounced. Results obtained showed that the research procedure adopted is a smart approach for damage assessment in reinforced concrete element

Nigerian Failed Developmental Strides: Can Agriculture Break the Jinx?

All over the world, industrialization is the principal underpinning of sustainable economic growth. But the attainment of industrialization and the accompanying economic stability that guarantee wellbeing for the population have not been that easy for the developing nations. In the free-for all quest for economic advancement, each people, nation, and continent adopt strategies it deems appropriate to pursue its goal. Agriculture have been a common denominator for all nations of the earth, whether developed or under developed. That has been the starting point for the advanced nations through the primitive age to the industrial revolution age to the present information/knowledge worker’s age. As they transited from one age to the other, they made use of acquired knowledge and available resources to move forward. Africa also started with agriculture through the primitive age to the current information/knowledge worker’s age without much to show in terms of economic stability and wellbeing of it citizens. This can be traced to the various approaches they adopted towards industrialization. Before independence, most African countries experienced sustainable growth with agriculture as the core activity. After independence, the discovery and exploitation of various types of mineral resources made many African nations to loose focus in agriculture thereby turning them to major importers of food. Over the recent years, Nigeria being one of such nations is faced with the burden of increasing food importation bill which in the near future may become unsustainable, there by creating crises that will destabilize the nation

Effect of Climate Change Pollutants on the Corrosion Rate of Steel in Rural, Urban and Industrial Environments

Ever since industrial revolution, the world climatic conditions have been deteriorating due to the ever increasing amount of air pollutants injected into the atmosphere. This has adversely affected the health of living organism, plants and the environment that host them. Building structures are not left out in the devastating effects of air pollution as metallic components are easily oxidized leading to corrosion. Corrosion of steel materials due to environmental pollutants has become an issue of great concern to researchers all over the world. This paper looked at the effect of climate pollutants in the air as they affect weathering steel in rural, urban and industrial environment. The corrosion process in steel over time and how it varies in rural, urban and industrial environments were considered. The overall objective of this work is to underscore the factors that have impact on the progressive deterioration of materials exposed to atmospheric weathering. The climate and air pollution parameters that affect material losses are identified and their numeric values obtained vie dose response functions. The results obtained show tha

Environmental Effect of Climate Change Pollutants Loading on Structural Steel Stresses

Human activities on earth it is observed is having negative impact on the continuous existence of life on the planet. This is as a result of build-up of gases that tend to affect life and well-being of plants and animals including structures put in place to support them. Structural failure as a result of pollutant exposure does not occur unless where there is wrong design of the structure or the owner has not carried out routine maintenance. The effect of such loss on structure in place need to be further studied to engender better understanding of structural failure possibilities or its reliability. This work looked at the effect of gases such as SO2 and humidity known as climate change gases in the air and their effect on steel structures, specifically bridges, in rural, urban and industrial locations. It was shown also that for these three types of locations, the moment resistance and shear resistance of structures overtime will decrease by 3% and 4.6% respectively. However, the deflection of the same structure will increase by 1% over the same time range. The implication will be an increase in the cost of design and construction as a result of increased thickness of steel structures and additional paint coating to reduce this negative effect

Quality Management in Construction Project: Empirical Study of Covenant University Sports Complex

The acceptable level of quality in construction projects has long been a problem. Significant resources are wasted on construction projects because of inefficient or non-existent quality management procedures. Therefore, this study evaluates the quality management and the quality grading practices in the construction project with emphasis on the Covenant University Sports Complex. The quantitative research strategy and questionnaire survey were used as the main data collection instrument for soliciting information from the project participants in order to determine the best key for quality management practice. Moreover, an ultrasonic pulse velocity tester was engaged to assess and evaluate the conditions of concrete structural members. It was found out that management commitment to quality is the most key for effective quality management practices in the construction project. In addition, the ultrasonic pulse velocity (UPV) test carried out on the randomly selected structural members varied in the range 4.2km/sec to 4.6km/sec. From this, it is inferred that the quality grading and homogeneity of concrete in the tested reinforced concrete columns, beams and slabs fall in the range of “good to excellent concrete”. The findings would assist project participants in implementing an efficient quality grading and management while executing construction projects

The Role of Construction Materials in Building Collapse in Nigeria: A Review

Building failure or collapse happens both in the developed and developing countries but the rate of occurrence in the developing country such as Nigeria is quite alarming and therefore call concern. The menace of building collapse in Nigeria is very alarming and appalling. Building collapse in Nigeria has become the norms they are easily swept under the carpet whenever it occurs. It is rather unfortunate that both human and economic loss we record each time there is a failure or building collapse is rather humongous. There is also a lot of blame game among professional stakeholders in the industry once failure or collapse of building occur and unfortunately, there is no proper scientific investigation in most developing countries such as Nigeria to ascertain the cause of failure or collapse as the case may be in order to avoid any future occurrence. In the cause of this review, it was discovered that building materials such as reinforcing steel, cement, sand, granite, sandcrete blocks and concrete play huge important role in either the collapse or stability of buildings in Nigeria. The roles of these materials are so vital that they contribute immensely to the collapse of buildings. It was concluded that 10-25% of buildings that collapse in Nigeria are as a result of the use of poor quality building materials. The review has extensively dealt with building collapse in relation with the role of building materials during construction

In vivo evaluation of the antiviral activity of Cajanus cajan on measles virus

Cajanus cajan, a tropical shrub, serves as source of food and traditional medicines. The evaluation of aqueous and ethanol extracts for activity against measles virus and toxicity to embryonated chicken eggs was carried out in this study. In vivo and in vitro assay techniques using embryonated chicken eggs and tissue culture (Hep-2 cell lines) as media for both virus cultivation and anti-virus assay showed that a hot-water extract yielded higher activity against measles virus. The hot-water extract of the stem yielded a Log2 titre of 0.1 for the in vivo assay and an inhibition of cytopathic effect (CPE) in Hep-2 cells by 100% for the in vitro assay. At all concentrations of the extracts, there was a lowering of virus concentration (p = 0.05), indicated by hemagglutination (HA) titration, which is the advantage of HA titration over the tissue culture technique using CPE. This study validates embryonated chicken eggs as suitable media for anti-virus assay and the use of C. cajan in the treatment of some diseases of viral origin

Strength and microstructure of eco-concrete produced using waste glass as partial and complete replacement for sand

The sustainable benefits of waste glass usage in concrete include the possibility of reducing solid waste and greenhouse gas emission and preservation of raw materials. This current study examines the effect of recycled waste glass as a partial and complete substitute for natural sand in producing eco-friendly concrete. The recycled waste glass was proportioned in levels of 25, 50, 75 and 100% by weight to substitute sand in the concrete using a mix ratio of 1:2:4 (cement:sand:gravel) at a W/C ratio of 0.5 targeting 20 MPa strength at 28 days. Tests, which include X-ray fluorescence (XRF), were conducted on the waste glass and cement materials; slump test was performed on the freshly prepare concrete at different percentage glass content. Compressive and tensile strength tests were performed on 60 specimens after 3, 7, 28 and 90 days of curing. The concrete microstructure was examined using the scanning electron microscope (SEM). Results showed that workability and the mechanical strength of the concrete produced decreased with increasing waste glass content. However, concrete containing 25% and 50% waste glass contents showed significant enhancement in strength, but it is recommended that the optimum glass content should be 25% for the production of sustainable eco-concrete

Performance of concrete modified with discarded glass at elevated temperatures for sustainable construction

This study examines the residual strength of concrete produced with crushed discarded soda-lime glass as aggregates after exposure to elevated heating. The natural aggregates, which comprise both the coarse and fine aggregates were partially and completely replaced by 0, 25, 50, 75 and 100% of the discarded glass. The control and samples containing crushed discarded glass aggregates were prepared at constant water-cement ratio (w/c) of 0.50 and the cube samples were exposed to temperatures of 60, 150, 300 and 500°C after curing in water for 90 days. The heating was increased at a constant heating rate of 10°C/min. The strength of the concrete samples was measured before and after exposure to heating after air-cooling of the heated samples. Moreover, scanning electron microscope (SEM) examination was carried out on selected samples to investigate the extent of change in the concrete bonding, especially at higher heating. Test results depict reduction trend in the characteristic strength of the tested samples as the level of heating increases, while the SEM micrographs reveal clear decomposition in the concrete interfaces. However, it was noticed from the results that concrete containing crushed discarded glass show better performance in terms of strength compared to the reference concrete at certain temperature exposure indicating a modified concrete with improved post-fire resistance

SIMULATED RESPONSE OF BUILDINGS TO EARTHQUAKE IN THE SOUTH-WESTERN REGION OF NIGERIA

Recent seismic alerts and warnings from researchers and agencies in Nigeria as regards earthquakes in the south-western part of Nigeria has led to earthquake forecast by few researchers. A team of researchers among other researchers forecasted an earthquake of magnitude 7.2 for the south-western region of Nigeria in the year 2028 while another team of researchers also forecasted an earthquake of ≥ 5.0 magnitude for the year 2028 in the same south-western region. In a bid to prepare towards these forecasted events, it necessary to design subsequent upcoming buildings around the lines of fault in the south west to resist the forecasted earthquake magnitudes. Hence this research carried out simulated response spectrum analysis on a typical modeled 3-story reinforced concrete building. The analysis was carried out using Etabs 2016 based on the specification of EURO Code 2004. The building demonstrated the highest drift of 0.010695 in the x-direction at story 2, highest deflection of 90mm in the x-direction at story 4, highest overturning moment of 36859.9947 KNm at the base and the highest stiffness of 190378.969 KN/m at story 1. To this end, the results of this response analysis should guide the designs and construction of buildings around the lines of fault in the south-western part of Nigeria in order to ensure safety of lives and properties in response to quakes in this region