A sabedoria é vã, sem o amor. iii Dedico este trabalho à minha esposa pelo apoio e incentivo mesmo durante minhas ausências. iv AGRADECIMENTOS À minha esposa pelo incentivo e apoio durante minhas ausências Ao Professor Francisco Antonio Rocco Lahr pela orientação, incentivo, amizade e especial atenção dedicada. Ao professor Carlito Calil Júnio, pela, orientação, amizade e especial atenção dedicada. À Universidade Estadual de Maringá, ao Departamento de Engenharia Civil e aos colegas de trabalho pela oportunidade de desenvolver este trabalho. À Prefeitura do Município de Piracicaba e à Cia. Rio Grande de Reflorestamento, pela atenção durante a execução dos trabalhos de campo. À instituição de fomento, CAPES/PICDT pela concessão da bolsa de estudos, à FAPESP pelo apoio financeiro e à EESC/USP-SET-LaMEM por colocar à minha disposição os recursos necessários.

With the possibility of developing simple connections, of easy execution, strong and durable, the bonded-in steel bars with structural resins have started being applied to different situations, such as shear connectors in mixed wood-concrete structures. These connectors, when steel bars are inclined in relation to the grain, may work under axial forces transmitting more stiffness and strength to the connection. In this research, the pull out strength of bonded-in steel bars was evaluated, bent 45° in relation to wood grain, using epoxy resin Sikadur-32 Fluid. In random sample of round pieces of Eucalyptus citriodora (Corymbia citriodora), CCA treated, with six replications in each observation, and considering the variability of the parameters: natural wood mechanical properties; apparent density; bar diameters; adherence surface and the moisture content. Steel bars used were highly resistant ones (CA-50), with threaded surface solicited by axial force, under monotonic loadings, with two consecutive load cycles. From the analysis of variance (ANOVA), the increase in the moisture content promoted reductions in the values of the compressive strength. The estimate of the pullout strength by the multivariable regression model, the moisture content was considered not significant, increases in the area of anchoring strengths implied significant increases in anchorage strength values, and the interaction between the factors (anchoring area and moisture content) promoted reductions in the anchor strength values of the steel bars.

The development of standard methods and criteria for the stress grading of structural timber elements by non-destructive, fast and cheap bending tests, will allow producers, distributors and customers of such elements, have a better control of the marketed product. This paper analyzes the most suitable length of free span for stress grading of structural timbers, number of points to be assayed in each element, data precision and evaluation of cost of these tests for small business.

After years of exposure in environmental conditions, the wood is subject to decay by chemical, mechanical, physical and biological agents. Consequently its physical and mechanical properties can be reduced, affecting their use. Timber used in bridge sustention columns is subject to intense decay process, mainly in outcrop area (area in contact to the ground), the most critical situation, because of the best combination of humidity e oxygen, factors that provide wood decay organisms. Decay process can be minimized with preventive maintenance, as wood impregnation with preservatives, before installation of the timber. After wood is installed, a periodical maintenance is necessary to conserve and prolong its life time. Thus, the aim of this study is to evaluate degradation occurred in timber columns used in Capela Bridge sustention, built with mixed system of wood and concrete, after 10-years-old of use. Located in Piracicaba - SP, Brazil, the bridge was made with Corymbia citriodora CCA-treated. The columns strength and degradation conditions were evaluated in 2 points with isntrumented driller. Point A was approximately 1,5 m of the ground and point B was in outcrop area. Instrumented driller results showed that all the columns, in both points, presented good strength and had no degradation level.

In Brazil, don't have a standard code which rules the shear connector tests for mixed woodconcrete structures. Due to the excellent connector diversification, regarding shape, stiffness, limit strength and the placement in the structural member; and variables as: spaces between connectors, spaces between connectors and the member ends of wood or concrete, dimension Original Research Article

The study of pull out strength of glued in rods perpendicularly to the grain is presented. Three types of resin were used in order to evaluate their efficiency. Additionally, the effects of the variation of the moisture content and of the glue line thickness were considered. The beams were made of wood from Corymbia citriodora, (ρ 12% = 1000 kg/m 3 ) and Pinus oocarpa Shiede (ρ 12% = 550 kg/m 3 ). The wood specimens (four samples for each type of test) were seasoned to the expected moisture contents of 12, 15, 18 and 22%. The anchorage length of the glued in rods was 80 mm, the hole diameters were 7.5, 8.5, 9.5 and 10.5 mm and their respective glue line thickness, 0.6, 1.1, 1.6 and 2.1 mm. The deformed reinforcing bars used as rods, with the minimum yield strength of 500 MPa, had nominal diameter of 6.3 mm. The obtained results confirmed the assumption that type of resin, moisture content, glue line thickness are strength determining factors, while density is less than others. The results are presented in a comparative form. The failure modes are discussed and the need of a broad understanding of resin behavior on wood was emphasized.

The pull out of steel bars bonded-in in structural wood pieces present highly satisfactory performance concerning esthetics, strength and connection stiffness, nevertheless, great concerns arise relating to the bonding quality control, making some authors suggest that the bonding operation must be done in a factory environment with the adequate quality control and by specialized people. Several studies have been published analyzing methods of production control or the effect of common contaminators, present in the bonding area which might affect the global capacity of the connection. In this work, anchorage strength was evaluated under the effects of four superficial treatments on the anchorage area of steel bars and increasing and decreasing moisture variations after bonding. The adhesive used was the epoxy resin Sikadur32 Fluid and the steel bars were perpendicularly fixed to the wood fibers, obtained through a random sample of a lot of sawed Corymbia citriodora wood. In 98.70% of rupture, specimen occurred due to loss of resin adhesion on the bar surface, due to chemical and mechanical loss adhesion.

The connections with bonded-in steel bars present excellent aesthetics, trustworthy performance, high strength and stiffness, and are more economic compared to the equivalent traditional mechanical connections. Nonetheless, their use in an economic and safe way depends on the deeply knowledge about influences on the pull out behaviour and on many different connection work conditions. Among these parameters, it can be pointed out with great relevance, the diameter variation of the bars used, which influence directly on the adherence surface on the anchorage area. In this work, the experiment was conducted in order to evaluate the effects of steel bar diameter variations of bonded-in with the epoxy resin Compound, in three directions (0, 45and 90º) between the rods and the wood fibers. The wood natural variability was considered through random sample of a batch of structural Pinus oocarpa Shiedetimbers. In each observation, with a total of seven combinations of variables, six replications were presented. The steel bars used were highly stiffness ones (CA-50), with threaded surface solicited into the axial direction under monotonic loadings, with two consecutive load cycles. Thereafter statistical analysis, the results are presented and commented in a comparative way.