Research on Engineering Structures and Materials

347-353

Authors: Matheus de Lima Nunes, Mauro de Vasconcellos Real

Port structures are usually large and are subject to heavy loads such as the stresses caused by a port crane and other equipment used during a port operation. Therefore, for a meticulous analysis of the internal forces of the port structures, with the intention to optimize and turn more effective the design, is essential the use of computational tools and advanced mathematical methods, as, for example, the Finite Elements Method. The Porto Novo of the Port of Rio Grande moves millions of tons of materials per year, becoming one of the main ports in Brazil. Its structure has gone through two stages of modernization making it possible the use of larger and more efficient port equipment, operation with ships of greater load capacity, and more quantity of mooring berths available for simultaneous operation. This study will be intended to perform the computational modeling of the Public Wharf of Porto Novo of the Port of Rio Grande using the finite element method through the ANSYS software to estimate the axial loads of the wharf piles when a Mobile Port Crane is in port operation.

367-377

Authors: Vinícius Avila, Mauro Real, Márcio Moura

Bridges in Brazil are designed according to design code NBR 7188:2013 [1] and NBR 7187:2003 [2], in which the moving load model is composed of a three-axle vehicle. The configuration of the moving load model follows the pattern of an older version of the code, the NB-6 (1960). Despite the updating of load values, the present moving load model is not appropriate to represent the current traffic effects in Brazilian bridges. The dynamic effects induced by the moving load are taken into account by the impact coefficient, applied in the load model. The static values of the load model are obtained by multiplying its load by this coefficient. The objective of this work is to perform a dynamic analysis of bridge girders, to determine the dynamic effects, to compare with the static effects and to measure the accuracy of the impact coefficient. The results obtained for the beams, showed that for some cases, the impact coefficients had a good approximation to transform the static efforts into dynamic ones. However, in other cases, these coefficients did not show the same result. Through the study it was possible to identify that the impact coefficients provided in the code can be enhanced from new studies taking into account the dynamic analysis of loadings of Brazilian bridges.

393-402

Authors: Rodrigo Reis Amaral, Grégori da Silva Troina, Carolina Martins Nogueira, Marcelo Langhinrichs Cunha, Luis Alberto Oliveira Rocha, Elizaldo Domingues dos Santos, Liércio André Isoldi

The present article presents a geometric evaluation of stiffened plates employing the symmetry boundary condition. The computational models were developed in the software ANSYS, based on the Finite Element Method, using the SHELL281 finite element. As expected, the numerical simulations considering the symmetry demonstrated a gain in computational processing because of the possibility of developing the models in a quarter of a plate rather than simulating the entire plate, without accuracy loss. The geometric configurations are obtained through the application of Constructal Design. For this, some geometric parameters are varied (degrees of freedom) and others are kept fixed (restrictions). After that, these plates with different geometries are numerically simulated and their mechanical behaviors (deflection and stress) are compared to each other through the Exhaustive Search Technique. Then, it is possible to define the stiffened plate that has the best mechanical behavior. For this, a reference plate without stiffeners was used. In this plate part of its volume of material was transformed into stiffeners by reducing the thickness of the same, thus maintaining the value of the length and the value of the width as constants. The objective here is to determine the geometric configurations that minimize the maximum deflection and the maximum von Mises stress of the stiffened plates. The obtained results showed that, by transforming part of the volume of the reference plate into stiffeners, structural stiffness gains can be achieved in the stiffened plates when compared with the values of deflection and stress reached by the reference plate.

415-426

Authors: Conceição J.E.M. Fortes, Rute Lemos, Ana Mendonça, Maria Teresa Reis

This paper describes the two-dimensional (2D) physical model tests of a rock armor breakwater, performed at LNEC´s experimental facilities, under the framework of the HYDRALAB+ project. The aim of the present work was to evaluate damage evolution under future climate change scenarios, by using different damage evaluation techniques. The tested wave conditions simulated a storm sequence where two water levels (low water and high water) were considered, as well as an increase of the wave height. The water levels and the wave heights were chosen to simulate extreme events forecasted on climate change scenarios. Damage evaluation was based on the traditional counting method and on stereo-photogrammetric techniques. Test results are presented in terms of the damage parameter S and in terms of the percentage of removed armor units. The analysis is focused on the damage progression during the scale model tests, for the imposed storm sequence. The damage presents an oscillating behavior with two main damage areas corresponding to the active zones for each level, due to the variation of the water level between low-water and high-water. This behavior differs significantly from that found for the common storm sequences usually tested, where the water level does not change. Both measuring techniques lead to an intermediate damage of the cross-section breakwater. However, the damage parameter assessment with the stereo-photogrammetric technique allows a more versatile evaluation, since it is possible to characterize damage in representative zones of the cross- section.

437-446

Authors: Marcelo Langhinrichs Cunha, Emanuel da Silva Diaz Estrada, Grégori da Silva Troina, Elizaldo Domingues dos Santos, Luiz Alberto Oliveira Rocha, Liércio André Isoldi

This work is a feasibility study of a Genetic Algorithm (GA) based geometric optimization of stiffened plates subjected to transverse loads. For that, the Constructal Design method was used in order to define the search space, aiming to minimize the stiffened plate’s central deflection, while keeping the total volume of material constant. The number of longitudinal Nls and transverse Nts stiffeners and the relation hs/ts, the ratio between the height and the thickness of the ribs, were considered as degrees of freedom of the studied optimization problem. In order to estimate the displacement field of the plate reinforced with stiffeners, the Finite Element Method (FEM) was used through the ANSYS® Mechanical APDL software. For the verification, the results obtained in the present study were compared with those obtained by Troina (2017), which used Exhaustive Search (ES) as optimization technique. The results indicated that is more efficient using GA than ES since the former requires the analysis of a lesser amount of cases in order to determine the optimal geometric configuration; there being reductions of up to 47,09% on the number of simulations.