Finite element model to predict structural response of predamaged RC beams reinforced by toughness-improved UHPC under unloading status

2021 ◽  
Vol 235 ◽  
pp. 112019
Author(s):  
Yanping Zhu ◽  
Yang Zhang ◽  
Xingliang Li ◽  
Genda Chen
2014 ◽  
Vol 107 ◽  
pp. 190-204 ◽  
Author(s):  
Enzo Martinelli ◽  
Annalisa Napoli ◽  
Bruno Nunziata ◽  
Roberto Realfonzo

2016 ◽  
Vol 11 (1) ◽  
pp. 11-21 ◽  
Author(s):  
Marco Domaneschi ◽  
Maria Pina Limongelli ◽  
Luca Martinelli

The paper focuses on extending a recently proposed damage localization method, previously devised for structures subjected to a known input, to ambient vibrations induced by an unknown wind excitation. Wind induced vibrations in long-span bridges can be recorded without closing the infrastructure to traffic, providing useful data for health monitoring purposes. One major problem in damage identification of large civil structures is the scarce data recorded on damaged real structures. A detailed finite element model, able to correctly and reliably reproduce the real structure behavior under ambient excitation can be an invaluable tool, enabling the simulation of several different damage scenarios to test the performance of any monitoring system. In this work a calibrated finite element model of an existing long-span suspension bridge is used to simulate the structural response to wind actions. Several damage scenarios are simulated with different location and severity of damage to check the sensitivity of the adopted identification method. The sensitivity to the length and noise disturbances of recorded data are also investigated.


Author(s):  
Sungchan Kim ◽  
Insik Nho ◽  
Takkee Lee ◽  
Kyungsik Choi

The interaction between a ship and sea ice is a complex process depending on the ice properties, the ice geometry and the relative velocity between the ship and the ice. The effect of important parameters such as ship speed and ice thickness on the impact force are studied by means of finite element model. Idealized ice element types are applied to finite element model in order to survey the impact force and the structural response of icebreaker ARAON subjected to sea ices. Interaction behaviors obtained by finite element model considering the varying parameters are also discussed to compare the numerical results with the design data of ARAON.


2000 ◽  
Vol 7 (6) ◽  
pp. 333-341 ◽  
Author(s):  
Lloyd Hammond ◽  
Raphael Grzebieta

This paper presents the results of a series of small-scale underwater shock experiments that measured the structural responses of submerged, fully clamped, air-backed, steel plates to a range of high explosive charge sizes. The experimental results were subsequently used to validate a series of simulations using the coupled LS-DYNA/USA finite element/boundary element codes. The modelling exercise was complicated by a significant amount of local cavitation occurring in the fluid adjacent to the plate and difficulties in modelling the boundary conditions of the test plates. The finite element model results satisfactorily predicted the displacement-time history of the plate over a range of shock loadings although a less satisfactory correlation was achieved for the peak velocities. It is expected that the predictive capability of the finite element model will be significantly improved once hydrostatic initialisation can be fully utilised with the LS-DYNA/USA software.


2017 ◽  
Vol 14 (03) ◽  
pp. 1750032 ◽  
Author(s):  
Prabin Pathak ◽  
Y. X. Zhang ◽  
Xiaodan Teng

This paper investigates the structural behavior of fiber reinforced polymer (FRP) strengthened reinforced concrete (RC) beams by developing a new simple, efficient and accurate finite element model (FEM-B). In addition to the FRP, concrete and steel rebars, the adhesive and stirrups which have been generally ignored in the reported models from literatures are considered in the new models. At first, a finite element model (FEM-P) is developed assuming perfect bond between concrete, FRP and adhesive interfaces. Then the FEM-P model is expanded to form the FEM-B model by including the bond-slip effect between concrete, FRP and adhesive interfaces. The developed new finite element models (FEM-B and FEM-P) are validated against experimental results and demonstrate to be effective for the structural analysis of FRP strengthened RC beams. Furthermore, parametric studies are carried out to learn the effects of types and thickness of FRP on the structural behavior of FRP strengthened RC beams based on the FEM-B model. The research findings are summarized finally.


2016 ◽  
Vol 2 (11) ◽  
pp. 576-589 ◽  
Author(s):  
Mohamed A. Sakr ◽  
Tarek M. Khalifa ◽  
Walid N. Mansour

Strengthening of reinforced concrete (RC) beams with externally bonded fibre reinforced polymer (FRP) plates/sheets technique has become widespread in the last two decades. Although a great deal of research has been conducted on simply supported RC beams, a few studies have been carried out on continuous beams strengthened with FRP composites.  This paper presents a simple uniaxial nonlinear finite-element model (UNFEM) that is able to accurately estimate the load-carrying capacity and the behaviour of RC continuous beams flexurally strengthened with externally bonded FRP plates on both of the upper and lower fibres. A 21-degree of freedom element is proposed with layer-discretization of the cross-sections for finite element (FE) modelling. Realistic nonlinear constitutive relations are employed to describe the stress-strain behaviour of each component of the strengthened beam. The FE model is based on nonlinear fracture mechanics. The interfacial shear and normal stresses in the adhesive layer are presented using an analytical uncoupled cohesive zone model with a mixed-mode fracture criterion. The results of the proposed FE model are verified by comparison with various selected experimental measurements available in the literature. The numerical results of the plated beams (beams strengthened with FRP plates) agreed very well with the experimental results. The use of FRP increased the ultimate load capacity up to 100 % compared with the non-strengthened beams as occurred in series (S). The major objective of the current model is to help engineers’ model FRP-strengthened RC continuous beams in a simple manner.


2016 ◽  
Vol 846 ◽  
pp. 440-445
Author(s):  
Prabin Pathak ◽  
Yi Xia Zhang

A new simple, efficient and accurate finite element model denoted as FEM-B is developed for the analysis of structural behavior of FRP strengthened RC beams with bond-slip effect. Geometric nonlinearity and material nonlinear properties of concrete and steel rebar are accounted for this model. Concrete, steel, FRP and adhesive are modelled as Solid 65, Link 180, Shell181 and Solid 45 respectively. Concrete is modelled using Nitereka and Neal’s model for compression, isotropic and linear elastic model before cracking for tension and strength gradually reduces to zero after cracking, whereas steel is assumed to be elastic perfectly plastic material. The material of FRP is considered to be linearly elastic until rupture, and adhesive is assumed to be linearly elastic. The bond slip between concrete, adhesive and FRP is based on the bilinear law, which is modelled using spring element Combin 39.The developed new finite element model FEM-B is validated against experimental results, and demonstrates to be effective for the structural analysis of FRP strengthened RC beams.


2018 ◽  
Vol 29 (18) ◽  
pp. 3562-3571 ◽  
Author(s):  
Vijay Venkatesh ◽  
Robert Northcutt ◽  
Christian Heinemann ◽  
Vishnu Baba Sundaresan

The incorporation of a shear-force (SF) feedback in scanning electrochemical microscopy (SECM) hardware has enabled topographically resolved electrochemical imaging of electroactive substrates. Despite the versatility of SECM-SF imaging, structural response of the ultra-microelectrode (UME) to various excitation inputs is poorly understood and predictive mathematical models for characterizing dynamic behavior, particularly at high operating frequencies (>100 kHz), are absent. In this article, we present a finite element model to characterize SF behavior by modeling the UME as a rigid cantilever with two distributed piezoelectric wafers (dither and receiver) and demonstrate the model’s ability to predict experimentally observed SF behavior. The obtained SF response under different dither-to-receiver distances for various UME geometries and loading conditions provides insight to the optimum placement of piezoelectric wafers on the UME for achieving a high SF amplitude at SF-sensitive frequencies. In addition, the variations in SF response under different dither-to-receiver orientations indicate the existence of a system transfer function that is dependent on the operating modes of the receiver. The agreement between simulated and experimental results suggests that the finite element model along with the experimental methodology can be extended to automated SF imaging using SECM hardware.


2019 ◽  
Vol 161 (A4) ◽  

River sea vessels are ships for inland navigation and suitable for restricted navigation at sea in regions where, -significant wave height does not exceed 2m, according to Bureau Veritas Rules for the classification of inland vessels. In a container vessel structure, almost the entire deck space is occupied by hatches, leaving a narrow strip of deck plating outboard. This calls for a topside structure of heavy plating or a double hull to provide material in tension, stiffness against lateral and torsional loads, and resistance to buckling in compression when the vessel is in sagging condition. For sea going open deck vessels, torsional loading plays a predominant part to the hull girder strength and for inland navigation open deck vessels; the effect of torsion is rather negligible. Keeping this scenario in mind, the aim of this project is to investigate the hull strength of a river sea container vessel under combined bending and torsional loading to study the effect of torsion on river sea open deck vessel. To perform the strength analysis, firstly, a finite element model is created using Femap with NX Nastran software for the investigated vessel. Therefore, still water and wave loads are calculated using direct calculation. To find out the still water loads Argos software is used and for the wave induced loads potential flow software Hydrostar is used. Next, Finite element model is verified with classical beam theory and thin wall girder theory. Then the effect of various loading conditions on structural response is investigated. After, structural response of different hull configurations are scrutinized under combined bending and torsional loading. Finally, some recommendations are proposed for structural response of river sea container vessel subjected to combined bending and torsional loading.


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