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Numerical simulation of the constructive steps of a cable-stayed bridge using ANSYS
Paula M. Lazzari,Américo Campos Filho,Bruna M. Lazzari,Alexandre R. Pacheco,Renan R. S. Gomes 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.3
This work addresses a three-dimensional nonlinear structural analysis of the constructive phases of a cable-stayed segmental concrete bridge using The Finite Element Method through ANSYS, version 14.5. New subroutines have been added to ANSYS via its UPF customization tool to implement viscoelastoplastic constitutive equations with cracking capability to model concrete’s structural behavior. This numerical implementation allowed the use of three-dimensional twenty-node quadratic elements (SOLID186) with the Element-Embedded Rebar model option (REINF264), conducting to a fast and efficient solution. These advantages are of fundamental importance when large structures, such as bridges, are modeled, since an increasing number of finite elements is demanded. After validating the subroutines, the bridge located in Rio de Janeiro, Brazil, and known as “Ponte do Saber” (Bridge of Knowledge, in Portuguese), has been numerically modeled, simulating each of the constructive phases of the bridge. Additionally, the data obtained numerically is compared with the field data collected from monitoring conducted during the construction of the bridge, showing good agreement.
Bruna M. Lazzari,Américo Campos Filho,Paula M. Lazzari,Alexandre R. Pacheco 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.4
ANSYS is a software well accepted by professionals and academics, since it provides a variety of finite elements, material constitutive models, and linear and nonlinear analysis of structures in general. For the concrete material, for instance, the software uses an elastoplastic model with the Willam-Warnke surface of rupture (1975). However, this model is only available for finite elements that do not offer the possibility of use of the element-embedded model for rebars, demanding a much larger amount of elements to discretize structures, making numerical solutions less efficient. This study is, therefore, about the development of a computational model using the Finite Element Method via ANSYS platform for nonlinear analysis of reinforced and prestressed concrete beams under plane stress states. The most significant advantage of this implementation is the possibility of using the element-embedded rebar model in ANSYS with its 2D eight-node quadratic element PLANE183 for discretization of the concrete together with element REINF263 for discretization of rebars, stirrups, and cables, making the solutions faster and more efficient. For representation of the constitutive equations of the steel and the concrete, a proposed model was implemented with the help of the UPF customization tool (User Programmable Features) of ANSYS, where new subroutines written in FORTRAN were attached to the main program. The numerical results are compared with experimental values available in the technical literature to validate the proposed model, with satisfactory results being found.
Structural analysis of a prestressed segmented girder using contact elements in ANSYS
Paula M. Lazzari,Américo Campos Filho,Bruna M. Lazzari,Alexandre R. Pacheco 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.3
Studying the structural behavior of prestressed segmented girders is quite important due to the large use this type of solution in viaducts and bridges. Thus, this work presents a nonlinear three-dimensional structural analysis of an externally prestressed segmented concrete girder through the Finite Element Method (FEM), using a customized ANSYS platform, version 14.5. Aiming the minimization of the computational effort by using the lowest number of finite elements, a new viscoelastoplastic material model has been implemented for the structural concrete with the UPF customization tool of ANSYS, adding new subroutines, written in FORTRAN programming language, to the main program. This model takes into consideration the cracking of concrete in its formulation, being based on fib Model Code 2010, which uses Ottosen rupture surface as the rupture criterion. By implementing this new material model, it was possible to use the three-dimensional 20-node quadratic element SOLID186 to model the concrete. Upon validation of the model, an externally prestressed segmented box concrete girder that was originally lab tested by Aparicio et al. (2002) has been computationally simulated. In the discretization of the structure, in addition to element SOLID186 for the concrete, unidimensional element LINK180 has been used to model the prestressing tendons, as well as contact elements CONTA174 and TARGE170 to simulate the dry joints along the segmented girder. Stresses in the concrete and in the prestressing tendons are assessed, as well as joint openings and load versus deflection diagrams. A comparison between numerical and experimental data is also presented, showing a good agreement.
Gabriela G. Machado,Américo Campos Filho,Paula M. Lazzari,Bruna M. Lazzari,Alexandre R. Pacheco 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.2
The design of segmental bridges, a structure that typically employs precast prestressed concrete elements and the balanced cantilever construction method for the deck, may demand a highly complex structural analysis for increased precision of the results. This work presents a comprehensive numerical analysis of a 3D finite element model using the software ANSYS, version 21.2, to simulate the constructive deck stages of the New Guaiba Bridge, a structure located in Porto Alegre city, southern Brazil. The materials concrete and steel were considered viscoelastic. The concrete used a Generalized Kelvin model, with subroutines written in FORTRAN and added to the main model through the customization tool UPF (User Programmable Features). The steel prestressing tendons used a Generalized Maxwell model available in ANSYS. The balanced cantilever constructive steps of a span of the New Guaiba Bridge were then numerically simulated to follow the actual constructive sequence of the bridge. A comparison between the results obtained with the numerical model and the actual vertical displacement data monitored during the bridge's construction was carried out, showing a good correlation.
Greco Raffaella,Lazzari Lorenzo,Xue Elisabetta,Assanelli Andrea,Marktel Sarah,Giglio Fabio,Clerici Daniela,Lupo Stanghellini Maria Teresa,Corti Consuelo,Bernardi Massimo,Ciceri Fabio,Peccatori Jacopo 대한감염학회 2019 Infection and Chemotherapy Vol.51 No.4
Invasive fungal diseases (IFDs) are a leading cause of infection-related-mortality after allogeneic hematopoietic stem cell transplantation (HSCT). In this prospective pilot study, we investigated the use of bedside lung ultrasound (US) in IFD management. Ten consecutive hematological patients, who developed pulmonary IFD after HSCT, were included in the study. Standard computed tomography scan and lung US were performed at IFD diagnosis and 10 days after antifungal treatment. The lung US demonstrated a high sensitivity in the detection of lung lesions at IFD diagnosis and in the follow-up examinations. It is of potential clinical relevance for IFD management in hematological patients.
Health-Related Quality of Life, Depression and Anxiety in Hospitalized Patients with Tuberculosis
Santos, Ana Paula Cere dos,Lazzari, Tassia Kirchmann,Silva, Denise Rossato The Korean Academy of Tuberculosis and Respiratory 2017 Tuberculosis and Respiratory Diseases Vol.80 No.1
Background: Much of the attention of tuberculosis (TB) programs is focused on outcomes of microbiological cure and mortality, and health related quality of life (HRQL) is undervalued. Also, TB patients have a significantly higher risk of developing depression and anxiety compared with those in the general population. We intend to evaluate the HRQL and the prevalence of symptoms of depression and anxiety in hospitalized patients with TB. Methods: Cross-sectional study in a tertiary care hospital in Brazil. Adult patients with pulmonary TB that were hospitalized during the study period were identified and invited to participate. HRQL was measured using the Medical Outcomes Study Short Form-36 (SF-36) version 2. Hospital Anxiety and Depression Scale (HADS) was used to record symptoms of anxiety and depression. Results: Eighty-six patients were included in the analysis. The mean age of all patients was $44.6{\pm}15.4$ years, 69.8% were male, and 53.5% were white. Thirty-two patients (37.2%) were human immunodeficiency virus positive. Twenty-seven patients (31.4%) met study criteria for depression (HADS depression score ${\geq}11$) and 33 (38.4%) had anxiety (HADS anxiety score ${\geq}11$). Scores on all domains of SF-36 were significantly lower than the Brazilian norm scores (p<0.001). Conclusion: The present study shows that TB patients may have a poor HRQL. Additionally, we found a possible high prevalence of depression and anxiety in this population. Health care workers should be aware of these psychological disorders to enable a better management of these patients. The treatment of these comorbidities may be associated with better TB outcomes.
Antonio Poerio,Matilde Sartoni,Giammichele Lazzari,Michele Valli,Miria Morsiani,Maurizio Zompatori 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.10
The epidemic of 2019 novel coronavirus, later named as coronavirus disease (COVID-19), began in Wuhan, China in December 2019 and has spread rapidly worldwide. Early diagnosis is crucial for the management of the patients with COVID-19, but the gold standard diagnostic test for this infection, the reverse transcriptase polymerase chain reaction, has a low sensitivity and an increased turnaround time. In this scenario, chest computed tomography (CT) could play a key role for an early diagnosis of COVID-19 pneumonia. Here, we have reported a confirmed case of COVID-19 with an atypical CT presentation showing a “double halo sign,” which we believe represents the pathological spectrum of this viral pneumonia.