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

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

Structural health monitoring and damage detection for composite panel structures via statistical analysis

Rectangular panels with or/and without mass loading are widely applied in civil,aerospace and mechanical engineering. Changes such as cracks, corrosion or drilled holes can affect the structure and integrity of components. This study focuses on three (3) parts of experimental works: firstly, to fabricate the three types of composite materials panels; secondly, to assess the mechanical properties, the micro structure and thermal analysis of the materials, and thirdly, to detect the damage by using smart sensor to appraise the Structural Health Monitoring (SHM) technique and damage identification. To do this, aluminium alloy type 6061-T6 and three fabricated composite materials are utilized. These composites are combined with epoxy resin as a matrix mixed individually with Twill Weave 240 g/m² carbon fiber (CFW), Plain Weave 300 g/m² Glass Fiber (GFW) and Chopped Strand Mats 450 g/m² glass fiber [GF (CSM)] as fillers. This study also includes the fabrication procedure of the three types of composite panels by using hand lay-up and vacuum bagging process. Al 6061-T6 is considered as a reference material in order to evaluate the characterizations of the new composite materials. Moreover, each material has a case study and eventually this research has four case studies. The first case (undamaged) is considered as a reference or the baseline standard data. Crack’s damages are simulated variedly in the panels to reflect the three damage cases in length such as 10 mm, 15 mm and 20 mm. Piezoelectric ceramic Lead Zirconate Titanate (PZT) transducer as a sensor is used to acquire the real time data. The comparison is carried out for damage detection and identification, based on the natural frequency approach and power spectrum with accuracy performance via signal from smart sensor (PZT). Root Mean Square Deviation (RMSD) index and Frequency Reduction Index (FRI) as statistical analysis methods for damage magnitude are performed to improve the SHM technique. RMSD out coming improves the damages identification, when the crack is increased RMSD is increased as well. Finally, SHM approach using PZT is improved and eventually very noticeable and probable changes in the natural frequency are observed, particularly when the damaged depth is increased in the composites. Meanwhile, the comparison between the CFW reinforced epoxy resin and the two glass fiber reinforced epoxy include the micro structure, thermoplastic analysis and mechanical properties. In general, CFW as a composite improved a higher micro structure, thermal analysis and mechanical properties and higher resistance against the vibration effect which is more than the two types of investigated glass fibers

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