Plank (tongue and groove) wood decking is a product that is commonly used in post and beam timber construction to transfer gravity loads on roofs and floors. In 2010, The National Building Code of Canada changed the application area of the specified concentrated roof live loads from 750 mm x 750 mm to 200 mm x 200 mm. The change was made to better reflect the area which a construction worker with equipment occupies. Preliminary analysis showed that the change in the application area of concentrated loads may have a significant impact on the design of decking systems. Little research or development has been done on plank decking since the 1950’s and 1960’s. An experimental program was undertaken at the University of Ottawa’s structural laboratory to better understand the behaviour of plank decking under uniformly distributed and concentrated loads. Non-destructive and destructive tests were conducted on plank decking systems to investigate their stiffness and failure mode characteristics under uniformly distributed as well as concentrated loads. The experimental test program was complimented with a detailed finite element model in order to predict the behaviour of a plank decking system, especially the force transfer between decks through the tongue and groove joint. The study showed that the published deflection coefficients for uniformly distributed loads can accurately predict the three types of decking layup patterns specified in the Canadian Design Standard (CSA O86, 2009). For unbalanced uniformly distributed loads on two-span continuous layup, it was found that the deflection coefficient of 0.42 was non-conservative. It was also found that under concentrated loads, the stiffness of the decking system increased significantly as more boards were added. A deflection coefficient of 0.40 is appropriate to calculate the deflection for the three types of decking layup patterns specified in the Canadian Design Standard (CSA O86, 2009) under concentrated load on an area of 200 mm by 200 mm. Significant load sharing was observed for plank decking under concentrated loads. An increase in capacity of about 1.5 to 2.5 times the capacity of the loaded boards was found. Furthermore, it was found that placing sheathing on top of a decking system had a significant effect in the case of concentrated load with an increase of over 50% in stiffness and over 100% in ultimate capacity.

Plank (tongue and groove) wood decking is a product that is commonly used in post and beam timber construction to transfer gravity loads on roofs and floors. In 2010, The National Building Code of Canada changed the application area of the specified concentrated roof live loads from 750 mm x 750 mm to 200 mm x 200 mm. The change was made to better reflect the area which a construction worker with equipment occupies. Preliminary analysis showed that the change in the application area of concentrated loads may have a significant impact on the design of decking systems. Little research or development has been done on plank decking since the 1950’s and 1960’s. An experimental program was undertaken at the University of Ottawa’s structural laboratory to better understand the behaviour of plank decking under uniformly distributed and concentrated loads. Non-destructive and destructive tests were conducted on plank decking systems to investigate their stiffness and failure mode characteristics under uniformly distributed as well as concentrated loads. The experimental test program was complimented with a detailed finite element model in order to predict the behaviour of a plank decking system, especially the force transfer between decks through the tongue and groove joint. The study showed that the published deflection coefficients for uniformly distributed loads can accurately predict the three types of decking layup patterns specified in the Canadian Design Standard (CSA O86, 2009). For unbalanced uniformly distributed loads on two-span continuous layup, it was found that the deflection coefficient of 0.42 was non-conservative. It was also found that under concentrated loads, the stiffness of the decking system increased significantly as more boards were added. A deflection coefficient of 0.40 is appropriate to calculate the deflection for the three types of decking layup patterns specified in the Canadian Design Standard (CSA O86, 2009) under concentrated load on an area of 200 mm by 200 mm. Significant load sharing was observed for plank decking under concentrated loads. An increase in capacity of about 1.5 to 2.5 times the capacity of the loaded boards was found. Furthermore, it was found that placing sheathing on top of a decking system had a significant effect in the case of concentrated load with an increase of over 50% in stiffness and over 100% in ultimate capacity.

This paper gives the derivation of a method for determining the forces to be applied to these points which will simulate the load distributed over all the airplane.

A resistência à força cortante em lajes de pontes sem armadura transversal têm sido um aspecto preocupante nas verificações de estruturas de concreto estrutural construídas décadas passadas e está diretamente relacionado aos modelos de cálculo de resistência à força cortante e de largura colaborante empregados no caso de cargas parcialmente distribuídas próximas do apoio. Entretanto, não existem ainda estudos nacionais relacionados ao nível de acurácia e precisão das abordagens geralmente empregadas na prática de projetos de pontes no Brasil. Por esta razão, propõem-se apresentar uma contribuição às análises de resistência à força cortante em lajes de pontes com ênfase no modelo de cálculo da ABNT NBR 6118:2014. Para isto foram comparados os resultados experimentais e teóricos utilizando diferentes modelos de resistência à força cortante e uma base de dados construída a partir de 642 resultados experimentais. Posteriormente, alguns modelos experimentais foram explorados por meio de simulações numéricas em elementos finitos no intuito de avaliar o nível de aproximações desta abordagem e investigar a influência de parâmetros como mísulas na proximidade dos apoios. Dentre os principais resultados desta pesquisa destaca-se que o valor médio da relação entre a resistência à força cortante teórica e experimental Vexp/Vcal utilizando a ABNT NBR 6118:2014 variou de 2,145 a 1,140 conforme o modelo de largura colaborante utilizado. Enquanto isso, os modelos numéricos calibrados apresentaram relação Vexp/VMEF variando entre 0,95 e 1,01 e com coeficientes de variação menores que 15%. De maneira geral, identificou-se que os modelos de resistência à força cortante apresentam elevados níveis de dispersão entre resultados teóricos e experimentais no caso de lajes e faixas de laje e que os modelos mais usuais de definição da largura colaborante não são precisamente adequados para o caso de cargas parcialmente distribuídas próximas do apoio. / The shear strength in bridge slabs without transverse reinforcement has been a matter of concern in structural concrete structures checks built in the past decades and is directly related to the shear force and effective width calculation models employed in the case of partially distributed loads close to the support. However, there are still no national studies related to the level of accuracy and precision of the approaches commonly used in the practice of bridge projects in Brazil. For this reason, it is proposed to contribute to the shear strength analyzes in bridge slabs with emphasis on the calculation model of ABNT NBR 6118: 2014. For this, we compared the experimental and theoretical results using different models of shear strength and a database constructed from 642 experimental results. Subsequently, some experimental models were explored by means of numerical simulations in finite elements in order to evaluate the level of approximations of this approach and to investigate the influence of parameters such as greater thickness close to the supports. Among the main results of this research, it is worth noting that the average value of the relationship between theoretical and experimental shear strength Vexp/Vcal using ABNT NBR 6118: 2014 varied from 2,145 to 1,140 according to the effective width model used. Meanwhile, the calibrated numerical models showed Vexp/VMEF ratio varying between 0.95 and 1.01 and with coefficients of variation lower than 15%. In general, it was identified that the shear strength models present high levels of dispersion between theoretical and experimental results in the case of slabs and slab strips and that the most usual models of defining the effective width are not precisely adequate for the partially distributed loads close to the support in slabs.