scholarly journals An Innovative Construction Technique for Curved Structures

2020 ◽  
Vol 10 (13) ◽  
pp. 4465
Author(s):  
Alessio Cascardi ◽  
Francesco Micelli ◽  
Maria Antonietta Aiello
Keyword(s):  
Aspect Ratio ◽  
Analytical Model ◽  
Opposite Direction ◽  
Structural Member ◽  
Fiber Reinforced Polymer ◽  
Construction Technique ◽  
Mutual Contact ◽  
Curved Structures ◽  
Reinforced Polymer ◽  
Fiber Sheet

In the present paper, an innovative, recently patented technique for the construction of a curved structural member without scaffolds is proposed and illustrated. It consists of a Hinged Lifting Arch (HLA), using Fiber-Reinforced Polymer (FRP) bonded strips. In detail, a series of blocks are cut following an arch geometry and then aligned on the ground floor to bond a composite on their top surface. Moreover, impregnation of the polymeric adhesive is not allowed at the extremities of each block. The fiber sheet is applied continuously along the entire extrados. In this context, hinges are introduced, and the FRP-connected blocks can easily rotate in the opposite direction around the contact ends (i.e., hinges). Finally, the middle block is lifted up, and the arch takes the desired shape. Moreover, an analytical model is proposed and discussed for designing the proper aspect ratio of the blocks in order to ensure full mutual contact when the HLA is completely lifted. The advantages of the proposed technique relate to the absence of scaffolds and improved seismic strength against horizontal loads, thanks to the presence of the FRP, which limits the occurrence of hinges at the extrados.

scholarly journals An Innovative Construction Technique for Curved Structures

2020 ◽  
Author(s):  
Alessio Cascardi ◽  
Francesco Micelli ◽  
Maria Antonietta Aiello
Keyword(s):  
Roman Empire ◽  
Structural Strength ◽  
Fiber Reinforced Polymer ◽  
Masonry Building ◽  
Experimental Demonstration ◽  
Construction Technique ◽  
Curved Structures ◽  
Reinforced Polymer ◽  
Fiber Sheet ◽  
Curved Elements

The masonry building Heritage is appreciated for its aesthetic and historical value all around the world. The widespread presence of curved elements, such as arch, vault and dome express the relevant constructive abilities in the different historical epochs. These curved elements are characterized by architectural beauty, structural strength (especially against the gravity loads), thermal comfort and fire resistance. On the other hand, curved structures required scaffolding in order to be erected. The design, the construction and the dismantling of the scaffolds is typically time-consuming and expensive. In addition, the on-site working risk is related to time-interferences (e.g. in manpower working, at the same time, over and under scaffold). This technology dates back to the Era of the Roman Empire and it is currently still used, despite its limitations and disadvantages. In the present paper, an innovative technique (recently patented), aiming for the construction of a curved structural member without scaffolds, is proposed and illustrated. It consists in a Hinged Lifting Arch (HLA), using FRP (Fiber Reinforced Polymer) bonded strips. In details, a series of blocks are cut following an arch geometry and then aligned on the ground-floor in order to bond a composite on their top surface. Moreover, the impregnation of the polymeric adhesive is not allowed at the extremities of each block. The fiber sheet is applied continuously along the entire extrados. In this sense, hinges are introduced, in fact, the FRP-connected blocks are able to easily rotate, in the opposite direction, around the contact ends (i.e. hinge). Finally, the middle block is lifted-up and the arch takes the desiderated shape. In the first experimental demonstration, the natural calcareous stone was used, even if the proposed technique is totally material-independent. Moreover, an analytical model is proposed and discussed for designing the proper aspect ratio of the blocks in order to ensure the full mutual contact when the HLA is totally lifted up. The advantages of the proposed technique are related to the absence of scaffolds and improved seismic strength against horizontal loads thanks to the presence of the FRP, which limits the occurrence of hinges at the extrados.

Experimental and analytical behaviour of sandwich composites with glass fiber-reinforced polymer facings and layered fiber mat cores

2020 ◽  
Vol 54 (30) ◽  
pp. 4875-4887
Author(s):  
Lauren MacDonnell ◽  
Pedram Sadeghian
Keyword(s):  
Glass Fiber ◽  
Analytical Model ◽  
Sandwich Beam ◽  
Fiber Reinforced Polymer ◽  
Sandwich Beams ◽  
Sandwich Composites ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

This paper presents the results of experimental and analytical studies on the behaviour of sandwich beams fabricated with layered cores and glass fiber-reinforced polymer (GFRP) composite facings. The GFRP facings were fabricated using a unidirectional fiberglass fabric and epoxy resin, and the cores were fabricated using a thin non-woven continuous-strand polyester fiber mat with a thickness of 4.1 mm. A total of 30 sandwich beams with the width of 50 mm were prepared tested with five varying core configurations including cores made with one, two, or three layers of the fiber mat core and with or without the inclusion of intermediate GFRP layers. The specimens were tested up to failure under four-point bending at two different spans to characterize flexural and shear properties of the specimens. Two types of failure were observed, namely crushing of the compression facesheet and core shear. The load-deflection, load-strain, and moment-curvature behaviour were analyzed and using the results the flexural stiffness, shear stiffness, and core shear modulus were calculated. An analytical model was also developed to predict load-deflection behaviour and failure loading of sandwich specimens with varying core layouts. After verification, the analytical model was used for a parametric study of cases not considered in the experimental study, including additional GFRP and fiber mat core layers. It was shown that additional fiber mat core layers and the inclusion of intermediate GFRP layers can increase the strength and overall stiffness of a sandwich beam, while additional GFRP layers can only increase the overall stiffness of the system. The analytical model can be used to optimize the configuration of layered sandwich composites for cost effective rehabilitation techniques of culverts, pipelines, and other curved-shape structures where a thin, flexible core is needed to accommodate the curvature of the existing structure.

Study on Self-Sensing Performance of Graphene-Modified FRP Bars

2021 ◽  
Vol 896 ◽  
pp. 81-86
Author(s):  
Xiu Zhi Huang ◽  
Jia Hui Zhang ◽  
Xin Wang
Keyword(s):  
Stress Condition ◽  
Tensile Load ◽  
Structural Member ◽  
Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Sensing Technology ◽  
Frp Bar ◽  
Static Tensile ◽  
Changing Rate ◽  
Frp Bars

At present, the distributed long-gauge optical sensor on fiber reinforced polymer(FRP) bar cannot be manufactured through integrated production. On the other hand, the point-sensing technology of the self-sensing bar will cause deviations in structural health monitoring (SHM). To solve these issues, applying the graphene/epoxy on FRP members is a feasible method for the piezoresistive characteristics of graphene. In this paper, basalt FRP (BFRP) bars with graphene/epoxy film were tested under static tensile load and the resistance was measured at the same time until they were broken down. The results suggested that the changing rate of resistance was linearly correlated to the strain. This fact indicated that the graphene-modified BFRP bar can well reflect the stress condition of the structural member within a safe range.

scholarly journals Structural Stress Method to Evaluate Fatigue Properties of Similar and Dissimilar Self-Piercing Riveted Joints

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 359 ◽  
Author(s):  
Harish Rao ◽  
Jidong Kang ◽  
Garret Huff ◽  
Katherine Avery
Keyword(s):  
Fatigue Life ◽  
Analytical Model ◽  
Fiber Reinforced Polymer ◽  
Fatigue Properties ◽  
Structural Stress ◽  
Life Data ◽  
Reinforced Polymer ◽  
Riveted Joints ◽  
Cfrp Composite ◽  
Head Height

In this paper, we discuss the application of a simple Battelle structural stress model to evaluate the fatigue life of a self-piercing riveted (SPR) carbon-fiber-reinforced polymer (CFRP) composite to aluminum AA6111. The analytical model accounts for the forces and moments acting on the rivets to determine the structural stresses which were then plotted against the laboratory-generated fatigue life data. The master S-N curve determined in this study thus accounts for various factors such as the stacking configuration, rivet head height, and fatigue load ratios. The analytical model used in this study was able to collapse a large number of fatigue life data into one master S-N curve irrespective of stack-ups, rivet head height, and load ratios. Thus, the master S-N curve derived from the model can be used to predict the fatigue life of the SPR joints.

Analytical study on torsional behavior of concrete beams strengthened with fiber reinforced polymer laminates using softened truss model

2020 ◽  
pp. 136943322098169
Author(s):  
Muhanad M Majed ◽  
Mohammadreza Tavakkolizadeh ◽  
Abbas A Allawi
Keyword(s):  
Analytical Model ◽  
Computational Procedure ◽  
Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Truss Model ◽  
Torsional Behavior ◽  
Before And After ◽  
Polymer Laminates

This study aimed at evaluating the torsional capacity of reinforced concrete (RC) beams externally wrapped with fiber reinforced polymer (FRP) materials. An analytical model was described and used as a new computational procedure based on the softened truss model (STM) to predict the torsional behavior of RC beams strengthened with FRP. The proposed analytical model was validated with the existing experimental data for rectangular sections strengthened with FRP materials and considering torque-twist relationship and crack pattern at failure. The confined concrete behavior, in the case of FRP wrapping, was considered in the constitutive laws of concrete in the model. Then, an efficient algorithm was developed in MATLAB environment to accomplish the analysis, solve the appropriate equations, and calculate the torsional moment and angle of twist at all points. The parametric study considered the effect of effective fiber strain to reach a better prediction for the full torsional behavior. The model was able to predict the torsional behavior of the RC beams strengthened with FRP materials before and after cracking stages with reasonable accuracy.

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