Abstract This note presents an alternative method for static load tests on piles (and caissons). Called Equilibrium Method by its first proponents, the method was applied in some load tests in Brazil, in addition to being the object of theoretical studies conducted at the Federal University of Rio de Janeiro. The method consists, in each step, to keep the load constant for a period of time and then let it relax (not pumping the jack) until the displacement and the load reach mutual equilibrium. The stabilized displacement and the relaxed load (the so-called load and displacement in equilibrium) are considered for the load-displacement curve. The method has the advantage of producing the load-displacement curve close to that of a slow, stabilized test (incremental slow maintained load test), but with a shorter total execution time. The paper includes a short theoretical background and a review of the Brazilian experience.

Resumo O presente artigo apresenta alguns resultados da pesquisa de Rosa [1], que teve por objetivo verificar o efeito da fluência e retração do concreto na interação solo-estrutura. Foi analisada uma edificação com 17 pavimentos mais subsolo, em fundação mista, submetida à instrumentação de campo contemplando o monitoramento de recalques e deformação de alguns pilares, ao longo do processo construtivo. Foi possível comparar o projeto do calculista com uma análise numérica mais refinada. Também se comparou o projeto, sem considerar e considerando a interação solo-estrutura. Finalmente, os diferentes cenários de projeto foram confrontados com os resultados experimentais, tanto em relação aos recalques como aos esforços nos pilares instrumentados. Atenção particular foi dada ao efeito da consideração da fluência e retração do concreto na análise da interação solo-estrutura.

Abstract The paper presents some results from Rosa’s [1] research that aimed to verify the effect of creep and shrinkage of the concrete in soil-structure interaction. The construction consists in a 17 storeys building. It is set down on shallow foundation, in the central part of the construction, and steel piles, on the boundary. The structure was submitted to instrumentation during construction, including the monitoring of foundation settlements and columns deformation. It was possible to compare the structural design with a numerical refined structural analysis. Comparisons of the structural and foundation design with and without due consideration of soil-structure interaction are also presented. Finally, the different design assumptions were confronted with instrumentation results, both related to foundation settlements and to columns loading as well. Attention is pointed out on the effect of concrete creep and shrinkage in the soil-structure interaction analysis.