Structural Behavior of Interlocking Load Bearing Hollow Block Wall Panels With Stiffeners Under In-Plane Vertical and Lateral Loads

An experimental study was conducted at the Universiti Putra Malaysia to investigate the effect of stiffeners on the structural behavior of Putra interlocking load bearing hollow block wall panels under vertical and lateral loadings. Putra block building system, developed by the Housing Research Centre of Universiti Putra Malaysia, consists of three types of blocks namely stretcher, corner and half blocks. Six wall panels each with 0.9 m width, 1.0 m height and 0.15 m thickness were tested. These wall panels were divided into two sets, each containing three specimens, one with no stiffener and the other two were stiffened with 2 and 3 steel bars and cement grout respectively. The steel bars were placed along the perimeter of the wall panels. All test specimens were subjected to in-plane loading. For vertical load test, uniformly distributed vertical load was applied from zero until failure. In lateral load test, a constant vertical load was applied on the top of the wall, while in-plane lateral load was applied from zero until failure. The effect of stiffeners was investigated by comparing important parameters such as; vertical deflection as well as in-plane and out of plane lateral deflections, failure loads and failure patterns between the stiffened and un-stiffened wall panels. To evaluate the resistances of the wall panels with different stiffeners, strength, cracks pattern and deformation were recorded and analyzed. The results show a significant increase in strength capacity associated with reduction in both lateral and vertical deflections for the stiffened wall panels. In addition, there was reduction in the in-plane lateral deflection for wall panels under the effect of lateral load. A significant change in crack pattern and failure mechanism was also observed. Compressive strength and shear strength for wall panels under the effect of vertical and lateral load which stiffened with 2 and 3 reinforcement steel bars were increased as compared with un-stiffened wall panel. The compressive strength was increased by 21% and 33% for wall panels stiffened with 2 and 3 reinforcement bars respectively as compared with un-stiffened wall panel. And, the shear strength was increased by 50% and 68.7% for wall panels stiffened with 2 and 3 reinforcement bars respectively as compared with un-stiffened wall panel

A review on the vibration analysis for a damage occurrence of a cantilever beam

Identification of defects in structures and its components is a crucial aspect in decision making about their repair and total replacement. Failure to detect the faults has various consequences, and sometimes may lead to a catastrophic failure. The conducted research work reported analytical and experimental investigations on the effects of a crack on the cantilever steel beam with circular cross section. The objective of this review is to quantify and to determine the extent of the damage magnitude and the location of the cantilever beams. In analytical study, finite element method (FEA) software was used in developing the model. The results showed that, by monitoring the change of the natural frequency it is a feasible and viable tool to indicate the damage occurrence and magnitude. Unlike for small crack depth, the natural frequencies are not a good damage detector. Mode shapes indicated good sensitivity to detect the damage magnitude for all crack parameters. Frequency Reduction Index (FRI) and Modal Assurance Criteria (MAC) were found to be in order a feasible tool to find the magnitude of the damage in beam structures. While, Coordinate Modal Assurance Criteria (COMAC) and Curvature Change Index (CCI) were used to predict the location of the crack tested beams and proved to be feasible

An approach and experimental technique for damage detection of composite panels using PZT sensor

At present, the advanced composite materials have gained it acceptance in the aerospace, civil structures and mechanic industries and had increased dramatically from the late eighties to the beginning at this decade. This paper describes an experimental analysis of laminated composite panels made of three different types of fibers reinforced epoxy. The design and dimensions of Al-6061-T6 floor’s panels are taken, while the same design and dimensions of these composite panels are used as well. The objective is to compare the mechanical properties, microstructure and thermal plastic analysis of these laminated composites with AL 6061-T6 alloy characterizations. In addition, vibration analysis of composite’s panels is also performed using NI-LabVIEW and compared with experimental results of Al 6061-T6 panels

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Middle East Respiratory Syndrome Coronavirus (MERS-CoV) Seropositive Camel Handlers in Kenya

Middle East respiratory syndrome (MERS) is a respiratory disease caused by a zoonotic coronavirus (MERS-CoV). Camel handlers, including slaughterhouse workers and herders, are at risk of acquiring MERS-CoV infections. However, there is limited evidence of infections among camel handlers in Africa. The purpose of this study was to determine the presence of antibodies to MERS-CoV in high-risk groups in Kenya. Sera collected from 93 camel handlers, 58 slaughterhouse workers and 35 camel herders, were screened for MERS-CoV antibodies using ELISA and PRNT. We found four seropositive slaughterhouse workers by PRNT. Risk factors amongst the slaughterhouse workers included being the slaughterman (the person who cuts the throat of the camel) and drinking camel blood. Further research is required to understand the epidemiology of MERS-CoV in Africa in relation to occupational risk, with a need for additional studies on the transmission of MERS-CoV from dromedary camels to humans, seroprevalence and associated risk factors

Structural health monitoring and damage identification for composite panels using smart sensor

Real-time monitoring of structural integrity is an important challenge. This article presents the results of damage detection in real time for two materials: Al 6061-T6 and twill weave carbon fibre-reinforced epoxy composite. The natural frequency as a global dynamic technique was adopted and the structure was evaluated based on the change in the natural frequency. A square thin plate with simply supported edges was investigated under the effect of sinusoidal signal which was generated via mechanical vibration exciter to carry out the natural frequency of the panel. A smart sensor (piezoelectric ceramic lead zirconate titanate) bonded to the surface of the composite panel was used to capture the signals. Experiments demonstrate the effect of change in crack depth and the response of these panels. The results were measured via monitoring technique and evaluated using root mean square deviation index as statistical analysis

The Palestinian primary ciliary dyskinesia population: first results of the diagnostic, and genetic spectrum

BACKGROUND: Diagnostic testing for primary ciliary dyskinesia (PCD) started in 2013 in Palestine. We aimed to describe the diagnostic, genetic and clinical spectrum of the Palestinian PCD population. METHODS: Individuals with symptoms suggestive of PCD were opportunistically considered for diagnostic testing: nasal nitric oxide (nNO) measurement, transmission electron microscopy (TEM) and/or PCD genetic panel or whole-exome testing. Clinical characteristics of those with a positive diagnosis were collected close to testing including forced expiratory volume in 1 s (FEV1) Global Lung Index z-scores and body mass index z-scores. RESULTS: 68 individuals had a definite positive PCD diagnosis, 31 confirmed by genetic and TEM results, 23 by TEM results alone, and 14 by genetic variants alone. 45 individuals from 40 families had 17 clinically actionable variants and four had variants of unknown significance in 14 PCD genes. CCDC39, DNAH11 and DNAAF11 were the most commonly mutated genes. 100% of variants were homozygous. Patients had a median age of 10.0 years at diagnosis, were highly consanguineous (93%) and 100% were of Arabic descent. Clinical features included persistent wet cough (99%), neonatal respiratory distress (84%) and situs inversus (43%). Lung function at diagnosis was already impaired (FEV1 z-score median −1.90 (−5.0–1.32)) and growth was mostly within the normal range (z-score mean −0.36 (−3.03–2.57). 19% individuals had finger clubbing. CONCLUSIONS: Despite limited local resources in Palestine, detailed geno- and phenotyping forms the basis of one of the largest national PCD populations globally. There was notable familial homozygosity within the context of significant population heterogeneity