Journal of Structural Engineering & Applied Mechanics - Golden Light Publishing ® | Trabzon

Journal of Structural Engineering & Applied Mechanics


Indra Narayan Yadav Dr. kamal Bahadur Thapa

Analysis of Fatigue Strain, Fatigue Modulus and Fatigue Damage for the modeling of concrete plays a vital role in the evolution material behavior which is heterogeneous and anisotropic in nature. The Level-S nonlinear fatigue strain curve, fatigue modulus curve, residual strain curve of concrete in compression, tension, flexure and torsional fatigue loading were proposed using strain life approach. The parameters such as physical meaning, the ranges, and the impact on the shape of the curve were discussed. Then, the evolution model of fatigue modulus was established based on the fatigue strain, fatigue modulus, residual strain and secondary strain evolution model. The hypothesis of fatigue modulus is inversely related with the fatigue strain amplitude. The fatigue evolution of concrete damages the bond between material grains, changed the orientation of structure of molecules and affects the elastic properties resulting in the reduction of material stiffness and modulus by formation of microcracking, macro cracking, cracking and finally damage. This paper presents the Fatigue Strain Life Model and analysis of fatigue strain, fatigue modulus and damage parameters of concrete which is capable of predicting stiffness degradation, inelastic deformation, strength reduction under fatigue loading and experimental results were employed for the validation of the theoretical Model.

Mehmet Aydın KÖMÜR İbrahim Özgür DENEME

This study presents an experimental investigation on the dynamic characteristics of infilled Reinforced Concrete (RC) frames. For this purpose, a 1/3-scaled, one-bay, three-storey RC frame was produced and tested by using ambient vibration test. The experiments were performed on sequentially produced three specimens which use the same single reinforced frame. The infill walls were made of hollow clay brick. The frequency, mode shapes and damping ratios in the in-plane direction of patterns were obtained by six accelerometers. Fifteen-minute records under ambient vibration were taken for each model, and the dynamic characteristics were determined using the ambient response testing and modal identification software (ARTeMIS) program. The experiments showed that the infill walls significantly affected the frequency values and damping ratios of the frame system. As a result of this study, the presence of damaged/undamaged infill walls lead to an increase in the frequency values and the damping ratios for the first three modes of the frame systems. On the other hand, the natural frequency of the first three modes of with undamaged infill walls is more than those with damaged ones. While the damping ratios for undamaged infill walls were increased at first two modes and it was decreased at the third mode.

Sudhira De Silva Vijini Uthpala

Timber is widely used as a building material in the construction industry. As it is in short supply, there is now a high demand for timber in the construction industry. This has made waste timber utilization for construction important. Finger jointing can be used to connect two small pieces of waste timber. Machinery is now available in Sri Lanka to fasten, using finger jointing, the timber pieces that are used for the manufacture of furniture. As it is important to determine the structural properties of finger jointed timber, three point bending and compression tests using a Universal Testing Machine (UTM) were conducted on samples of selected timber species commercially available in Sri Lanka, in accordance with British Standard 73:1957 to determine these properties. Samples were finger jointed with a finger length of 19 mm using the adhesive, Fevicol SWR. Satin with its high resistance to bending is found to be the most suitable species for finger jointing. The tests carried out indicated that when finger jointed, the bending strength of Satin gets reduced by only 9.5%. In the compression parallel to grain test, Jak displayed the minimum reduction of 1.53% in its compressive strength. In the timber species tested, finger jointing was found to be 100% effective in resisting compression perpendicular to grain. The compressive strength of Pine is found to be increased by 27.39% when it is under compression perpendicular to grain. Strength classes of the timber species selected were identified from British Standard 5268-2:2002. According to the results of the statistical analysis made on the mechanical (both experimental and theoretical) properties of timber species available in Sri Lanka, Satin, Pine and Grandis are found to be suitable for finger jointing for use as structural elements. The compressive strength of finger jointed Grandis and Pine are found to be too poor for use as structural elements. Finger jointing of Teak is found to be cost effective. Finally, it is recommended that further studies be done on using finger jointed local timber waste.

Kemal Hacıefendioğlu Fahri Birinci

In this study, an experimental and numerical study is carried out to estimate the dynamic behavior of reinforced concrete minaret subjected to low temperatures during earthquakes. For this purpose, 1:20 reduced scale model of an actual reinforced concrete minaret was built in the laboratory. In order to estimate the effects of the seasonal low temperatures on the minaret, the model was placed into a large volume freezer and then were exposed to low temperatures of -50C, -100C, -200C and -300C, respectively. For each temperature, the model was taken outside the freezer and by using the shaking table, the maximum acceleration values at the top and middle region of the minaret were obtained with accelerometers mounted on the minaret. The maximum acceleration values illustrated that seasonal low temperatures affect seismic behavior of the prototype reinforced concrete minaret model.