EXPEDIENCY OF CHOICE OF CARDBOARD — POLYETHYLENE PIPES OF ROUND SECTION AS UNEXTRACTIVE PUSTOTOOBRAZOVATELEJ FOR MONOLITHIC REINFORCE-CONCRETE BEAM FLAGS OF CEILING

A study sent to the search of the most effective construction of unextractive pustotoobrazovatelej with the purpose of decline of weight and cost of monolithic reinforce-concrete beam flags of ceiling is undertaken in the article. The selection of materials is executed for unextractive pustoobrazovatelja on the basis of comparison of different materials on energy consumptions on their production. The new construction of unextractive pustoobrazovatelja is reasonable and offer with the use of cardboard-polyethylene pipe of round section. Recommendations are given on the parameters of pustoobrazovatelja depending on length of flight of ceiling flag. The methods of testing, analysis, design, study, comparison and generalization are applied. On the basis of comparison of totality of properties of different pustotoobrazovatelej (form, durability, inflexibility, moisture resistance, volume of substituting for a concrete, industrial applicability, labor intensiveness, jenergozatratnosti) the best pustotoobrazovatelem appeared offered cardboard-polyethylene pustotoobrazovatel’ made from the cardboard pipes of round section covered by polyethylene tape in 0,045 mm thick.

Digital Imagine Correlation (DIC) Method for Detecting Crack Development in Construction Materials Subject to Loading

The digital image correlation (DIC) technique is developed for identifying the crack development in brick wall and reinforced concrete beam. This method is tested on brick wall and reinforce concrete beam to evaluate the observation with various strain quantities and mesh sizes. The analysis results reveal that using the von Mises strain field will lead to fine precision of crack observation, and that clearer imagines can be obtained with smaller mesh sizes. This technique is capable of judging crack loading to predict crack occurrences.