Application of Prestressed CFRP Textiles for the Development of Thin- Walled Concrete Structural Elements

2019 ◽  
Author(s):  
Juan Pablo Osman Letelier ◽  
Alex Hückler ◽  
Mike Schlaich
Keyword(s):  
Prestressed Concrete ◽  
High Strength ◽  
Experimental Tests ◽  
Sustainable Construction ◽  
Structural Elements ◽  
Prestressing Steel ◽  
Thin Walled Structures ◽  
Reinforced Polymer ◽  
Thin Walled ◽  
Doubly Curved

<p>The success story of prestressed concrete is based on the utilization of high‐strength prestressing steel which enables large compressive forces to be introduced into the concrete. However, thin‐walled concrete structures often require considerable thicknesses for the sole purpose of preventing corrosion of the steel elements. In this paper the use of prestressed Carbon Fiber Reinforced Polymer (CFRP) for the development of thin‐walled concrete structural elements is briefly presented. The transition of material to stronger, lighter and corrosion‐resistant CFRP represents a significant improvement in concrete construction. Prestressing with CFRP elements leads to more slender and thereby more economical and durable structural elements. Through the additional prestressing of a reinforcement mesh, very light and highly rigid surface structures can be constructed. Prestressing technologies have been developed and adapted for specific applications i.e. slabs and doubly curved structural elements and validated by experimental tests. This paper shows that prestressed carbon reinforced concrete can be used for more durable and efficient thin‐walled structures, allowing for more sustainable construction.</p>

scholarly journals Experimental Nondestructive Test for Estimation of Buckling Load on Unstiffened Cylindrical Shells Using Vibration Correlation Technique

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Kaspars Kalnins ◽  
Mariano A. Arbelo ◽  
Olgerts Ozolins ◽  
Eduards Skukis ◽  
Saullo G. P. Castro ◽  
...  
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Cylindrical Shells ◽  
Laser Scanner ◽  
Experimental Tests ◽  
Buckling Load ◽  
Correlation Technique ◽  
Thin Walled Structures ◽  
Instability Point ◽  
Thin Walled

Nondestructive methods, to calculate the buckling load of imperfection sensitive thin-walled structures, such as large-scale aerospace structures, are one of the most important techniques for the evaluation of new structures and validation of numerical models. The vibration correlation technique (VCT) allows determining the buckling load for several types of structures without reaching the instability point, but this technique is still under development for thin-walled plates and shells. This paper presents and discusses an experimental verification of a novel approach using vibration correlation technique for the prediction of realistic buckling loads of unstiffened cylindrical shells loaded under axial compression. Four different test structures were manufactured and loaded up to buckling: two composite laminated cylindrical shells and two stainless steel cylinders. In order to characterize a relationship with the applied load, the first natural frequency of vibration and mode shape is measured during testing using a 3D laser scanner. The proposed vibration correlation technique allows one to predict the experimental buckling load with a very good approximation without actually reaching the instability point. Additional experimental tests and numerical models are currently under development to further validate the proposed approach for composite and metallic conical structures.

Multiscale modeling of reinforced/prestressed concrete thin-walled structures

2009 ◽  
Vol 2 (1) ◽  
pp. 69-89 ◽  
Author(s):  
Arghadeep Laskar ◽  
Jianxia Zhong ◽  
Y.L. Mo ◽  
Thomas T.C. Hsu
Keyword(s):  
Multiscale Modeling ◽  
Prestressed Concrete ◽  
Thin Walled Structures ◽  
Thin Walled

Modeling the Varying Dynamics of Thin-Walled Aerospace Structures for Fixture Design Using Genetic Algorithms

2011 ◽  
Vol 223 ◽  
pp. 652-661
Author(s):  
Mouhab Meshreki ◽  
Helmi Attia ◽  
József Kövecses
Keyword(s):  
Numerical Models ◽  
Research Work ◽  
Computational Effort ◽  
Computational Time ◽  
Fixture Design ◽  
Structural Elements ◽  
Thin Walled Structures ◽  
Thin Walled ◽  
High Flexibility ◽  
High Level

Fixture design for milling of aerospace thin-walled structures is a challenging process due to the high flexibility of the structure and the nonlinear interaction between the forces and the system dynamics. At the same time, the industry is aiming at achieving tight tolerances while maintaining a high level of productivity. Numerical models based on FEM have been developed to simulate the dynamics of thin-walled structures and the effect of the fixture layout. These models require an extensive computational effort, which makes their use for optimization very unpractical. In this research work, a new concept is introduced by using a multi-span plate with torsional and translational springs to simulate the varying dynamics of thin-walled structure during machining. A formulation, based on holonomic constraints, was developed and implemented to take into account the effect of rigid fixture supports. The developed model, which reduces the computational time by one to two orders of magnitude as compared to FE models, is used to predict the dynamic response of complex aerospace structural elements including pockets and ribs while taking into account different fixture layouts. The model predictions are validated numerically. The developed model meets the conflicting requirements of prediction accuracy and computational efficiency.

Application of Finite Strip Method in Vehicle Design: Part 2 of 2—Post Buckling Analysis of Thin Walled Structures

2011 ◽  
Author(s):  
Umesh Gandhi ◽  
Stephane Roussel ◽  
K. Furusu ◽  
T. Nakagawa
Keyword(s):  
Load Capacity ◽  
High Strength ◽  
Maximum Load ◽  
Element Formulation ◽  
Tangent Stiffness Matrix ◽  
Finite Strip ◽  
Thin Walled Structures ◽  
Non Linear ◽  
Post Buckling ◽  
Thin Walled

Thin walled parts of high strength steel, under compressive loads are likely to buckle locally, and then depending on geometry and material properties the section may continue to carry additional load. For the post buckling conditions the deformations are large but finite. Therefore we need to consider geometrical non linearity in the calculations. In this paper we are extending the linear finite strip element formulation to include geometrical non linearity. Method to derive secant and tangent stiffness matrix for non linear finite strip element is developed and then the element formulation is verified for inplane and center load on a plate using Newton Raphson solver. The new non linear finite strip element can be useful in estimating maximum load capacity (including post buckling) of thin walled structures from 2D data.

scholarly journals Buckling of thin-walled cylinders: experimental and numerical investigation

2010 ◽  
pp. 47-52
Author(s):  
Caitríona de Paor
Keyword(s):  
Chemical Engineering ◽  
Oil And Gas ◽  
High Strength ◽  
External Pressure ◽  
Storage Tanks ◽  
Diverse Range ◽  
Thin Walled Structures ◽  
Liquid Storage ◽  
Thin Walled ◽  
Cylindrical Tanks

Thin-walled structures, also known as shells, combine light weight with high strength and are used in a diverse range of fields including aerospace engineering, civil engineering and chemical engineering. Common applications of these shells include oil and gas storage tanks, powder or liquid storage tanks in pharmaceutical plants as well as airplane frames and ship bodies. Although these thin-walled shells have a wide variety of uses, this research is motivated by storage tank collapse in the process industry. Thin-walled cylindrical tanks common in the food and biotechnology sectors are prone to buckling (or inward collapse) due to accidentally induced internal vacuum. During the sterilisation process, steam can condense, causing a reduction in volume. This results in an equivalent increase in external pressure, triggering collapse, or buckling of the tank. Such a collapse, if it occurs, tends to be catastrophic resulting in the complete destruction of the vessel (see Fig.1). Notwithstanding ...

scholarly journals CREEP OF REINFORCED CONCRETE THIN-WALLED STRUCTURES TAKING INTO ACCOUNT REVERSE DEFORMATIONS

2020 ◽  
Vol 6 (159) ◽  
pp. 113-117
Author(s):  
O. Chuprynin ◽  
N. Sereda ◽  
A. Garbuz
Keyword(s):  
Reinforced Concrete ◽  
Material Properties ◽  
Concrete Structures ◽  
Design Stage ◽  
Reinforced Concrete Structures ◽  
Nonlinear Creep ◽  
Structural Elements ◽  
Thin Walled Structures ◽  
Proposed Model ◽  
Thin Walled

One of the main tasks, which is solved at the design stage of the reinforced concrete element, is the analysis of the stress-strain state, as well as the determination of the service life. The article is devoted to modeling of nonlinear creep of reinforced concrete structural elements taking into account damages and return of the creep. The high priority of the research topic is substantiated, the purpose and objectives are formulated. A combination of a plastic model with fracture mechanics is proposed to simulate the behavior of concrete in accordance with its characteristics, including not only stress and deformation, but also the degradation of its stiffness. The resulting equations of state correspond to the law reverse deformations. The finite element method is used to solve the boundary value problem. For the sake of numerical modeling of thin-walled structures, the use of special shell elements is proposed. The mathematical formulation of the problem of creep of reinforced concrete structural elements taking into account anisotropy of material properties and creep deformations and return of the creep is presented. Creep problems of thin-walled structural elements were solved with the help of developed software. Analyzed the deformation of reinforced concrete panel of cylinder. The analysis of the results allows us to judge the effectiveness of the proposed model as a whole. The equation of state reflects the anisotropy of the material properties and takes into account the damage, which allows for a reliable assessment of the strength, stiffness and durability of reinforced concrete structures. Conclusions about the adequacy of the analysis of reliability and durability of reinforced concrete structures using the proposed model.

scholarly journals A discussion for the reduction in the length of a prestressed concrete railway tie in time

2021 ◽  
Author(s):  
Niyazi Özgür Bezgin
Keyword(s):  
Prestressed Concrete ◽  
High Strength ◽  
Railway Track ◽  
Structural Elements ◽  
Track Maintenance ◽  
Concrete Shrinkage ◽  
Prestressing Force ◽  
Steel Wires ◽  
Practical Evaluation ◽  
And Performance

Increasing train speeds, contemporary requirements for reduced track maintenance costs and extended track service lives required the development and use of reinforced concrete and prestressed concrete ties. Railway engineers began to use concrete for their bi-block and monoblock railway ties heavily, following the development of an understanding for design and performance of concrete structures, production of high strength steel wires and preferable economy of prefabricated mass production for reinforced and prestressed concrete structural elements following the first half of 20th Century. Structural elements of a railway track such as reinforced or prestressed concrete ties have strict production tolerances that are not common for ordinary structural elements. Production of concrete railway ties takes place under strict dimensional control that ensures a nominal design gauge width for the railway track. Design specifications for prestressed monoblock ties frequently specify the gauge width and the shoulder width to be within 1 mm of the design width. However, prestressed concrete ties experience shortenings in length due to transfer of the prestressing force known as instant elastic shortening and shortenings due to concrete shrinkage and concrete creep in time that also relate to ambient relavite humidity. The author conducted numerous studies on the matter, showed by calculation, and observed experimentally that if unaccounted for, such shortenings can surpass the allowed tolerances in time and result in the rejection of the produced tie for use in the railway track. This paper refers to previous studies by the author that brought international attention on the issue and presents a thorough and a practical evaluation of time related changes in tie lengths for a particular design for prestressed concrete monoblock ties under varying ambient humidity conditions.

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