Abstract This article presents the modeling of a complete bolted connection based on a model with one bolt connecting two or three plates. Initially, the behavior of this model with one bolt is analyzed by comparing it with existing bibliography for 3 different types of applied load: tension, shear and a combination of these two. This model includes all necessary considerations: contacts between the plates and the nut, head and shank of the bolt; contact between the plates, as well as friction between them; and pre-load on the bolt. The model also responds properly to loads parallel and perpendicular to the contact surface between the plates, including prying action effects. These calibrated models are then introduced as super-elements in empty spaces left on the full connection, through a relatively simple process using the finite element software ANSYS®. Upon filling these spaces, two complete connection models are evaluated: one with a single plate and one between two T-stubs. The results obtained with these models are compared with standard forecasts. These two connection types have a practical application in the way they will be analyzed, and also as part of more complex connections: bolted girder splices (in the region of web beam), beam-to-column connections with splice plates or end plate connections, beam splices with end-plates, etc.
Abstract The Hercílio Luz suspension bridge, built in 1926, has been out of service since 1991 due to high corrosion levels and structural element impairment. A complete rehabilitation project was developed which included the replacement of the impaired items and foundation strengthening. For this, an auxiliary structure was employed to support the central span during the rehabilitation process. A carefully studied load transfer process, where the central span loading is transferred from the eye-bar towards the auxiliary structure will be performed. For this purpose, a synchronized jacking sequence will be used, which was predefined by means of numerical model analysis. All structural elements had their designs evaluated and some geometric changes were implemented. This paper presents all the methodology developed in the rehabilitation project of Hercilio Luz bridge, as well as the development stages up to the present date.
RESUMO O objetivo com este estudo foi investigar as características de silagens preparadas com um resíduo seco de padaria hidratado com soro ácido de leite ou água associado ou não à ureia. O experimento foi conduzido em um arranjo fatorial 3 (três níveis de hidratação: 250, 300 e 350 mL kg−1 de subproduto) × 3 (três níveis de aplicação de ureia: 0, 5 e 10 g kg−1 de subproduto) × 2 (dois líquidos usados na hidratação: soro ácido de leite ou água). Mini silos foram utilizados como silos experimentais e permaneceram fechados por 30 dias. Em geral, silagens hidratadas com soro ácido de leite apresentaram maior (P<0,01) produção de ácido lático (19,6 vs. 18,5 g kg−1 de matéria seca [MS]), ácido acético (2,5 vs. 1,8 g kg−1 de MS) e ácido propiônico (8,0 vs. 5,4 g kg−1 de MS), e menores (P<0,05) contagens de fungos (5,35 e 5,01 ufg g−1 de silagem fresca) comparadas às silagens hidratadas com água. A maior hidratação das silagens aumentou a produção total de ácidos (P<0,01) reduzindo os valores de pH; mas o aumento na hidratação reduziu (P<0,01) a recuperação de MS das silagens. Silagens hidratadas com água e soro ácido de leite a 250 mL kg−1 e combinado com 5 e 10 g kg−1 de ureia exibiram maior (P<0,05) recuperação de MS. Silagens de resíduo seco de padaria hidratadas com soro ácido de leite apresentaram melhor padrão fermentativo, podendo representar uma estratégia prática para evitar o descarte de ambos os subprodutos no ambiente.
SUMMARY The objective of this study was to investigate the characteristics of silages prepared with a dry bakery by-product hydrated with acid whey or water associated or not at urea. The trial was a 3 (hydration at three moisture levels: 250, 300, and 350 mL kg−1 of by-product) × 3 (three application rates of urea: 0, 5, and 10 g kg−1 of by-product) × 2 (liquid used at hydration: acid whey or water) factorial arrangement. Mini-silos were used as experimental silos and remained closed for 30 days. Overall, silages hydrated with acid whey had higher (P<0.01) production of lactic (19.6 vs. 18.5 g kg−1 of dry matter [DM]), acetic (2.5 vs. 1.8 g kg−1 of DM) and propionic acid (8.0 vs. 5.4 g kg−1 of DM), and lower (P<0.05) fungi counts (5.35 and 5.01 cfu g−1 of fresh silage) compared to silages hydrated with water. Increased hydration led to the higher production of total acids (P<0.01), decreasing silage pH; but increased hydration reduced DM recovery (P<0.01). Silages hydrated with water and acid whey at 250 mL kg−1 and combined at 5 and 10 g kg−1 of urea exhibited higher DM recovery (P<0.05). Silages of a dry bakery by-product hydrated with acid whey had a better fermentation pattern and could represent a practical strategy to avoid discarding both by-products into environment.