The purpose of the paper is to perform a static analysis of a thin-wall cold-rolled steel cross-section of a trapezoidal sheet by means of a mathematical model developed in ANSYS, commercially available software applications. The trapezoidal sheets are used typically as an external cladding which covers the structures of steel halls. Investigating into behaviour of the trapezoidal sheets subjected to extreme loads represents an urgent issue in wind engineering. A physical tension test has been performed in order to verify and confirm the mathematical model. Experiments have been performed to prove results of the static analysis into the behaviour of a load-carrying structure formed by a thin-wall cross-section.
Alkali activated concrete (AAC) are considered a promising building material. They show high strength, good durability, and good resistance to aggressive agents etc. But these good properties are controlled by the good design of the concretes.
The paper presents the results which were recorded for self-compacting AACs with the water to slag ratio 0.50 - 0.52. The resistance of these concretes to Na2SO4, NH4Cl and acetate acid is presented in this paper. These agents were selected because they represent agents which are present in compost or sewage.
Cracks in cover of reinforced and pre-stressed concrete structures significantly influence the ingress of deleterious species causing decrease in durability of these structures. The paper is focused on the effect of fracture process on two selected physical parameters of concrete -the electrical resistivity and the ultrasonic pulse passing time -which might be employed as the quality indicator of concrete cover within (nondestructive) procedure(s) of assessment of the structural durability. The concrete electrical resistivity and ultrasonic passing time were investigated here with respect to two variants of treatment of the test specimens' surface (the pre-dried surface and the wet surface). Test configuration of three-point bending of notched beam was utilized to control the crack propagation; the fracture process passed through several loading-unloading sequences between which the electrical resistivity and ultrasonic passing time readings over the fractured region were performed. Equivalent elastic crack model was used for estimation of the fracture advance (described via the effective crack length) at the loading stages corresponding to the resistivity and ultrasonic measurements. Relationships between changes of both the concrete resistivity and ultrasonic pulse passing time and the effective crack length is determined and discussed.
The paper is focusing on the investigation of the effective crack length obtained from bending test on concrete notched beams with the complementary measurements of ultrasound passing time through the tested concrete specimen. The ultrasound passing time measurements are performed on several stages of the fracture process along the specimen ligament for each tested notched beam. Gained results of the time of ultrasound pulse needed to pass through specimens' failure zone, i.e. its dependence on the crack length or opening, provide information which may help to identify the process of crack formation without the visible indications. The fracture tests are conducted for a set of specimens differing in the notch length. Changes of the ultrasound passing times with increasing effective crack length are observed and discussed.
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