Current Issue : January - March Volume : 2018 Issue Number : 1 Articles : 5 Articles
In general, the satisfactory seismic performance of timber buildings can be partially\nattributed to the material characteristics of the wood itself and to the lightness of its own structure.\nThe aim of this paper is to analyze the in-plane behavior of light timber walls panels through a series\nof monotonic and cyclic tests, and to evaluate how the sheathing material and the fixation to the\nbase influence the overall response of the wall. Five tests are presented and discussed while the\nreliability of an analytical method to predict the response of the walls is studied. The sheathing\nmaterial revealed to be important in the overall response of the wall. Moreover, the type of fixation to\nthe base also revealed to be important in the in-plane response of timber walls. In-plane stiffnesses,\nstatic ductility, energy dissipation and damping ratio have been quantified....
The restrained thermal expansion of a pretensioned strand causes thermal prestress loss during steam curing until\nsufficient bond strength develops. The amount of thermal prestress loss is directly related to the characteristics of the interfacial\nbond stressââ?¬â??slip relationship at different maturity phases of concrete. For a rational assessment, the bond stressââ?¬â??slip relationship\nneeds to be investigated experimentally at different maturity phases. In this study, a total of 12 pull-out tests were performed using\nseven-wire strand of 12.7 mm diameter, at different concrete equivalent ages of 7.8, 23.5, 53.8 and 85.2 h. Based on the test\nresults, an empirical model of the bond stressââ?¬â??slip relationship was developed. The model comprised four segments: a curvilinear\nascending region, a constant maximum region, a linearly descending region, and a region of constant frictional bond stress. The\ncharacteristic values in the model were expressed as functions of equivalent age. The model was able to predict the test results with\nreasonable accuracy....
Structural deterioration after a period of service can induce the failure of prestressed concrete cylinder pipes (PCCPs), with\nmicrocracks in the coating leading to the corrosion of the prestressed wires. In this paper, we propose the use of Brillouin optical\ntime-domain analysis (BOTDA) strain sensors for detecting the onset of microcracking in PCCP coating: the BOTDAstrain sensors\nare mounted on the surface of the PCCP, and distributed strain measurements are employed to assess the cracks in the mortar\ncoating and the structural state of the pipe. To validate the feasibility of the proposed approach, experimental investigations were\nconducted on a prototype PCCP segment, wherein the inner pressure was gradually increased to 1.6MPa. Two types of BOTDA\nstrain sensorsââ?¬â?the steel wire packaged fiber optic sensor and the polyelastic packaged fiber optic sensorââ?¬â?were employed in the\nexperiments. The experimental distributed measurements agreed well with the finite element computations, evidencing that the\ninvestigated strain sensors are sensitive to localized deterioration behaviors such as PCCP microcracking....
When subjected to loading or thermal shrinkage, reinforced concrete structures usually behave in a cracking state, which raises\nthe risk of bar corrosion from the working environment. The influence of cover cracking on chloride-induced corrosion was\nexperimentally investigated through a 654-day laboratory test on cracked reinforced concrete specimens exposed to chloride\nsolution.Theconcrete specimens have a dimension of 100mmÃ?â?? 100mmÃ?â?? 400mmand a single prefabricated crack at the midspan.\nWhen the percentage concentration of chloride ion (0.6%, 1.2%, 2.1%, 3.0%, and 6.0%) and crack width (uncracked, 0.2, 0.3, 0.4,\nand 0.5 mm) are taken as variables, the experimental results showed that the corrosion rates for cracked specimens increased with\nincreasing percentage concentration of chloride and increasing crack width. This study also showed the interrelationship between\ncrack width and percentage concentration of chloride on the corrosion rate. In addition, an empirical model, incorporating the\ninfluence of the cover cracking and chloride concentration, was developed to predict the corrosion rate. This model allows the\nprediction of the maximum allowable ...
In many cases, service life of reinforced concrete structures is severely limited by chloride penetration until the steel reinforcement\nor by carbonation of the covercrete.Water repellent treatment on the surfaces of cement-based materials has often been considered\nto protect concrete from these deteriorations. In this paper, three types of water repellent agents have been applied on the surface\nof concrete specimens. Penetration profiles of silicon resin in treated concrete have been determined by FT-IR spectroscopy.Water\ncapillary suction, chloride penetration, carbonation, and reinforcement corrosion in both surface impregnated and untreated\nspecimens have been measured. Results indicate that surface impregnation reduced the coefficient of capillary suction of concrete\nsubstantially. An efficient chloride barrier can be established by deep impregnation.Water repellent surface impregnation by silanes\nalso can make the process of carbonation action slow. In addition, it also has been concluded that surface impregnation can provide\neffective corrosion protection to reinforcing steel in concrete with migrating chloride.The improvement of durability and extension\nof service life for reinforced concrete structures, therefore, can be expected through the applications of appropriate water repellent\nsurface impregnation....
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