Damage Detection of Ferrocement Tanks Using Experimental Modal Analysis and Finite Element Analysis

In the recent years, structural health monitoring for civil structures using experimental modal analysis has been developed. Experimental modal analysis is the process of determining the dynamic parameters (frequencies, damping factors, modal vectors and modal scaling) of a linear, time invariant system by way of an experimental approach. It began in 1940’s in aircraft then it used in civil structures since the advent of the digital mini-computers and the digital Fast Fourier Transformation (FFT) spectrum analyzer in the early 1970’s. In this paper, the damage in ferrocement tank is detected experimentally by changing in its dynamic parameters due to two damages that were manufactured in its wall. Also in the current paper, theoretical models using ANSYS finite element software were developed to find the modal parameters of the healthy and damage tank. The current results showed that the theoretical models give accurate results in comparing with the theoretical results. Also the experimental modal analysis is quick, easy and inexpensive method to detect the damage in the ferrocement tank

Structural Behaviour of Ferrocement channels Beams

The main objective of this research is to study the structural behaviour of ferrocement concrete composite channels reinforced with various types of reinforcing materials. The dimensions of the developed ferrocement and control test specimens were kept constant as 100mm width, 200 mm height and 2000 mm length. The thickness of the two webs and base was kept constant as 25 mm. The test specimens were loaded under four lines loadings until failure.  The effects of the main parameters were extensively studied. High resistance ferrocement channels beams were developed with high crack resistance, high deformation characteristics,  high strength, high ductility and energy absorption properties could be used with great economic advantages  in the same way as steel channels in some of its uses and  very useful  for developed and developing countries alike

Experimental and FE simulations of Ferrocement Domes Reinforced with Composite Materials

The main objective of the current researches is estimating the structure performance of ferrocement domes reinforced with composite material. The current paper presented an experimental program included casting and testing up to failure four ferrocement domes. All specimens have 1000mm diameter and 500mm height; respectively and they were reinforced with welded wire meshes (for the first and second dome), fiberglass meshes (for the third dome) and polyethylene wire meshes (for the fourth dome). The second dome is the same as the first dome except that the second dome has two opening with 100x100mm dimensions to indicate the effect of the opening in the structure behavior of ferrocement dome. Also FE simulations for all tested domes were employed. The results of the experimental program indicated that the dome reinforced with fiberglass mesh has the highest service load and ultimate load and the dome reinforced with welded wire meshes achieved highest ductility ratio and energy absorption. Additionally comparing the results of FE simulations with the experimental results showed that the results of FE simulation is closed the experimental results

Structural behaviour of ferrocement channels slabs for low cost housing

This paper presents a new pre cast U-shape ferrocement forms reinforced with various types of metallic and non-metallic mesh reinforcement. This research was designed to investigate the feasibility and effectiveness of employing various types of reinforcing meshes in the construction of structural slabs incorporating permanent U-shape ferrocement forms as a viable alternative for conventional reinforced concrete slabs. Fiber glass meshes reinforcement was used for durability and protection against corrosion of reinforcing steel. To accomplish this objective, an experimental program was conducted. The experimental program comprised casting and testing ten slabs having the total dimensions of 500x100x2500 mm incorporating 40 mm thick U-shape permanent ferrocement forms. Series A consists of two conventionally reinforced concrete slabs were cast and tested and used as control slab without fibers and with fibers, volume fraction, 2.05 % and 2.177 %. Series B comprises of two slabs reinforced with one and two layers of expanded steel mesh, volume fraction 2.09 and 2.42% respectively. Series C comprises two slabs reinforced with two and four layers of welded galvanized steel mesh, having volume fraction 2.05 and 2.189% respectively. Series D Consists of two slabs reinforced with one layer and two layers of fiber glass meshes, having volume fraction 2.107 and 2.277% respectively. Series E comprises two slabs reinforced with 2 layers expanded steel mesh and one layer expanded steel mesh, having volume fraction 1.357 and 2.750 % respectively. The test specimens were tested as simple slabs under four-line loadings condition on a span of 2300mm. The performance of the test slabs in terms of strength, stiffness, strains, cracking behavior, ductility, and energy absorption properties was investigated. The behavior of the developed slabs was compared to that of the control slabs. The experimental results showed that high ultimate and serviceability loads, better crack resistance control, high ductility, and good energy absorption properties could be achieved by using the proposed slabs and low cost compared with control specimen

Comparative study of tricuspid valve repair using ring vs. synthetic band in severe functional tricuspid valve regurgitation

Background: Functional tricuspid valve regurgitation secondary to left-sided valve disease remains a common problem. There are different surgical techniques for tricuspid valve repair; however, the superiority of one approach over the other has not been proven. Our objective was to compare the short-term results of ring versus synthetic band annuloplasty to repair functional severe tricuspid regurgitation in patients with left-sided valve lesions. Methods: This retrospective study includes 60 patients who underwent left-sided valve replacement with concomitant tricuspid valve repair for severe tricuspid regurgitation. Patients were divided into group A (n= 30), patients with rigid rings, and group B (n= 30), patients with synthetic bands. Results: The preoperative demographic and clinical data were non-significant between both groups. In the preoperative data, the tricuspid annular plane systolic excursion (TAPSE) was significantly higher in the ring group (2.84 ± 0.53 vs. 2.3 ± 0.4, P< 0.001). Hospital stay was more prolonged in group B (10.05 ± 1.57 vs. 11.7 ± 2.76 days, P=0.006). There were no differences in other operative and postoperative data between groups. After a six-month follow-up, both groups had no significant difference regarding the clinical data or the degree of tricuspid valve regurgitation. Conclusion: Tricuspid valve annuloplasty with a rigid ring or synthetic band for tricuspid regurgitation could have a good short-term outcome

Early Results of Coronary Artery Bypass Grafting Surgery with or without Coronary Endarterectomy

Background: Managing patients with diffuse coronary artery disease is challenging. The advantages of coronary endarterectomy (CE) combined with coronary artery bypass grafting (CABG) compared to CABG alone are controversial. This study compared short-term outcomes, including ICU and hospital stays, arrhythmias, postoperative myocardial infarction, renal impairment, and hospital mortality, between patients who underwent CABG without and with CE. Methods: This randomized controlled study included 100 patients who underwent CABG with or without CE. Participants were randomly allocated into two equal groups. Group I (n=50) included patients who underwent CABG alone, and Group II (n=50) included patients who underwent CABG combined with CE. Results: The right coronary artery was the most common vessel affected by CE (44%), followed by the left anterior descending artery (42%). Low-output syndrome and pleural effusion were more frequently observed in Group II; however, these differences did not reach statistical significance. There was no difference in postoperative complications or ejection fraction between the groups. The ICU stay was significantly longer in Group II (3.02±0.84 vs. 2.58±0.5 days; p=0.007). Additionally, patients in Group II had significantly longer hospital stays (14.48±1.87 vs. 11.98±1.35, p<0.001). Conclusion: Compared with CABG alone, CABG with CE might not be associated with increased short-term mortality or morbidity. CABG with CE was associated with prolonged hospitalization, necessitating a careful assessment of the benefits versus an extended hospital stay when considering this adjunctive procedure

Effect of aggregates with high gypsum content on the performance of concrete

Sulfates in fine aggregate are a major problem when it exists in excessive amount especially in the Middle East and Iraq. Most of sulfate salts in fine aggregate are composed of calcium, magnesium, potassium and sodium sulfates. Calcium sulfates is the most common salt present in fine aggregate. It is usually finding as gypsum. It is difficult to obtain the specific sulfates content in fine aggregate within standard specifications. This research was conducted to investigate the effect of adding different contents of gypsum to fine aggregate as a replacement by weight on some properties of two types of concrete {self-compacted concrete (SCC) and high strength concrete (HSC)}. In these work three bases mixes of each type of concrete are used: mixes with different contents of metakaolin, mixes with different contents of gypsum and mixes incorporating different contents of metakaolin and gypsum. This study is devoted to determine the allowable content of sulfates in fine aggregate. Three levels of gypsum were tested (0.5, 1, 1.5) % by weight of fine aggregate and three levels of metakaolin were tested (5, 10, 15) % by the weight of cement. The experimental program is devoted to produce concrete with different levels of metakaolin and gypsum and determine its mechanical properties such as compressive strength and splitting tensile strength. The results arrived from this work show that the optimum gypsum content was 1.5% by weight of fine aggregates for mixes of SCC which gives increases in compressive strength and tensile strength, and 1% gypsum for mixes of HSC, results showed also that the metakaolin improved the properties of the two types of concrete and increased the loss which caused by sulfates. The best mix ever in SCC is 1% gypsum with 5% metakaolin, and 1% gypsum with 10% metakaolin for HSC

Experimental and numerical study of the behavior of RC slabs with openings reinforced by metal mesh under impact loading

The main objective of the following work is to inspect the effect of reinforcing metal mesh on the behavior of slabs with openings under impact loadings. Based on an earlier numerical study by Shaheen et al. (2017), slabs with mid-side openings revealed the worst behavior regarding to deflection and cracked pattern when subjected to impact loading compared to other slabs with different locations of openings. Hence, the present work focuses specifically on this type of slabs and the variation in their behavior when reinforced by welded or expanded metal mesh. Seven specimens were prepared and tested in Faculty of Engineering, Menoufia University, Egypt. Moreover, a FE model for the slabs was built using Abaqus 6.14 and verified against test results. It was found that expanded metal mesh had a significant effect on reducing deflection due to impact load as well as controlling of cracks in contrast with welded metal mesh

Pre- and Post-Fire Strength Assessment of Ferrocement beams

The results of an experimental investigation on the behavior of ferrocement beams after exposed to fire are presented in this paper. Different types of steel meshes are used compared with conventional reinforcement. The experimental program comprised casting and testing of eighteen beams having the dimensions of 100mm×100mm×1000mm. Three beams were reinforced as a conventional reinforcement. Each control beam was reinforced with two steel bars of diameter 8 mm in tension, two steel bar of diameter 6mm in compression and stirrups of 6 mm diameter placed at 200 mm intervals. The ferrocement beams were reinforced with steel meshes without any stirrups. Two types of steel meshes were used to reinforce the ferrocement laminate. These types are: square welded wire fabric, and expanded wire mesh. Single layer, double layers and three layers of square welded wire mesh were employed. Single layer and double layers of expanded wire mesh were employed. The experimental program was classified into three groups. First group was tested without exposure to fire, the second group was tested after exposure to fire for six hours and the last group was tested after exposure to fire under loading. All specimens were tested under 4-points flexural loadings. The performance of the test beams in terms of strength, stiffness, cracking behavior and energy absorption was investigated. The results showed that high serviceability and ultimate loads, crack resistance control, and better deformation characteristics could be achieved by using the proposed ferrocement forms

Behavior of Hexagonal Concrete-Filled Double-Skin Steel Short Columns under the Effect of Axial Compression

Concrete-filled double skin tubular (CFDST) columns involve a tube-‌in-‌tube arrangement, where the steel sections can be round, square or rectangular hollow sections, with the annulus between the hollow sections filled with concrete. To date there have been no significant applications of hexagonal concrete-filled double skin tubular columns (HCFDST) with inner circular tubes worldwide, partly due to the lack of design provisions. This paper addresses the compressive performance of these columns. To obtain the structural behavior of HCFDST columns, a finite element analysis was conducted. To indicate the accuracy and the reliability of the model, the proposed FEM model was verified by the available experimental data for HCFDST. Columns were employed to conduct parametric studies, the effects of various parameters on the load-displacement response of HCFDST short columns are studied by using the validated FE model. A new formula to determine ultimate load for regular HCFDST short columns in compression has been proposed in this study