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Lessons from the analysis of a 3-D concrete shear wall
Vecchio, F.J. Techno-Press 1998 Structural Engineering and Mechanics, An Int'l Jou Vol.6 No.4
A three-dimensional static nonlinear finite element analysis was performed on the NUPEC large-scale flanged shear wall, which was the subject of an international study program. Details of the constitutive models and analysis procedures used are provided, and the results of the analysis are presented and discussed. The analytical results are compared to the experimentally observed behaviour, and reasonable correlation is observed. Deficiencies in the modelling are identified. In addition, a parametric study is undertaken to investigate factors and mechanisms influencing both the observed behaviour and the calculated response. Finally, a cyclic load analysis of the wall is described and discussed. The paper serves to point out aspects in modelling that are critical to both producing realistic results, and correctly interpreting those results.
Approximate analyses of reinforced concrete slabs
Vecchio, F.J.,Tata, M. Techno-Press 1999 Structural Engineering and Mechanics, An Int'l Jou Vol.8 No.1
Procedures are investigated by which nonlinear finite element shell analysis algorithms can be simplified to provide more cost effective approximate analyses of orthogonally-reinforced concrete flat plate structures. Two alternative effective stiffness formulations, and an unbalanced force formulation, are described. These are then implemented into a nonlinear shell analysis algorithm. Nonlinear geometry, three-dimensional layered stress analyses, and other general formulations are bypassed to reduce the computational burden. In application to standard patch test problems, these simplified approximate analysis procedures are shown to provide reasonable accuracy while significantly reducing the computational effort. Corroboration studies using various simple and complex test specimens provide an indication of the relative accuracy of the constitutive models utilized. The studies also point to the limitations of the approximate formulations, and identify situations where one should revert back to full nonlinear shell analyses.
Compression field modeling of confined concrete
Montoya, E.,Vecchio, F.J.,Sheikh, S.A. Techno-Press 2001 Structural Engineering and Mechanics, An Int'l Jou Vol.12 No.3
The three-dimensional behavior of confined concrete was investigated, including strength enhancement due to triaxial compressive stresses, lateral expansion, compression softening, cover spalling and post-peak ductility. A finite element program based on a nonlinear elasticity methodology was employed to evaluate the ability to model triaxial behavior of reinforced concrete (RC) by combining constitutive models proposed by several researchers. The capability of compression field based models to reproduce the softening behavior of lightly cracked confined concrete was also investigated. Data from tested specimens were used to evaluate the validity of the formulations. Good agreement with the experimental results was obtained.
Vahid Sadeghian,Frank Vecchio 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.2
FormWorks-Plus is a generalized public domain user-friendly preprocessor developed to facilitate the process of creating finite element models for structural analysis programs. The lack of a graphical user interface in most academic analysis programs forces users to input the structural model information into the standard text files, which is a time-consuming and error-prone process. FormWorks-Plus enables engineers to conveniently set up the finite element model in a graphical environment, eliminating the problems associated with conventional input text files and improving the user’s perception of the application. In this paper, a brief overview of the FormWorks-Plus structure is presented, followed by a detailed explanation of the main features of the program. In addition, demonstration is made of the application of FormWorks-Plus in combination with VecTor programs, advanced nonlinear analysis tools for reinforced concrete structures. Finally, aspects relating to the modelling and analysis of three case studies are discussed: a reinforced concrete beam-column joint, a steel-concrete composite shear wall, and a SFRC shear panel. The unique mixed-type frame-membrane modelling procedure implemented in FormWorks-Plus can address the limitations associated with most frame type analyses.
C. E. Zhou,F. J. Vecchio 한국계산역학회 2005 Computers and Concrete, An International Journal Vol.2 No.6
This paper describes a 2D nonlinear finite element analysis (NLFEA) platform that combines heat flow analysis with realistic analysis of cracked reinforced concrete structures. The behavior models included in the structural analysis are mainly based on the Modified Compression Field Theory and the Distributed Stress Field Model. The heat flow analysis takes into account time-varying thermal loads and temperature-dependent material properties. The capability of 2D nonlinear transient thermal analysis is then implemented into a nonlinear finite element analysis program VecTor2?for 2D reinforced concrete membranes. Analyses of four numerical examples are performed using VecTor2, and results obtained indicate that the suggested nonlinear finite element analysis procedure is capable of modeling the complete response of a concrete structure to thermal and mechanical loads.
Tools for forensic analysis of concrete structures
Evan C. Bentz,Frank J. Vecchio,Michael P. Collins 한국계산역학회 2004 Computers and Concrete, An International Journal Vol.1 No.1
Computer-based analysis tools for forensic assessment of reinforced concrete structures are presented. The analysis tools, mostly in the form of nonlinear finite element procedures, are based on the concepts and formulations of the Modified Compression Field Theory. Relevant details regarding their formulation are provided. Development of realistic constitutive models and corroboration of the analysis procedures, through comprehensive experimental programs, are discussed. Also presented are graphicsbased pre- and post-processors, which are of significant aid in structural modeling, input of data, and interpretation of analysis results. The details and results of a case study, illustrating the application and value of such analytical tools, are also discussed.
Lijia Xu,Nicole Grandi,Claudia Del Vecchio,Daniela Mandas,Angela Corona,Dario Piano,Francesca Esposito,Cristina Parolin,Enzo Tramontano 한국미생물학회 2015 The journal of microbiology Vol.53 No.4
HIV-1 reverse transcriptase (RT) is still an extremely attractivepharmaceutical target for the identification of new inhibitorspossibly active on drug resistant strains. Medicinalplants are a rich source of chemical diversity and can be usedto identify novel scaffolds to be further developed by chemicalmodifications. We investigated the ability of the main lignansfrom Schisandra chinensis (Turcz.) Baill. fruits, commonlyused in Traditional Chinese Medicine, to affect HIV-1 RTfunctions. We purified 6 lignans from Schisandra chinensisfruits and assayed their effects on HIV-1 RT and viral replication. Among the S. chinensis fruit lignans, Schisandrin Band Deoxyschizandrin selectively inhibited the HIV-1 RTassociatedDNA polymerase activity. Structure activity relationshiprevealed the importance of cyclooctadiene ring substituentsfor efficacy. In addition, Schisandrin B was also ableto impair HIV-1 RT drug resistant mutants and the earlyphases of viral replication. We identified Schisandrin B andDeoxyschizandrin as new scaffold for the further developmentof novel HIV-1 RT inhibitors.