ISSN:2630-5763
Journal of Structural Engineering & Applied Mechanics
ARTICLES
Umut Ufuk Doğan
Ahmet Can Altunışık
Mustafa Ergün
In this study, it is aimed to be searched the effect of the rebar on the structural behavior of reinforced concrete bridges formed with the finite element method. For this purpose, the numerical model of the bridge with known dimensions, material properties and rebar configuration was modeled using ANSYS finite element analysis program. In the first model, it was thought that the bridge was constructed using only concrete, rebar was not taken into consideration. Then the same bridge was modelled without changing the boundary conditions as if it was built by reinforced concrete material in which rebar and concrete were together and the modal analyses were carried out on this model again. The dynamic characteristics of the two different bridge models were determined using numerical methods and the effect of the rebar on these characteristics
was presented by comparing them with each other. When the results obtained were examined, it was found that the rebar had no significant effect on the modal behavior of the bridge. Thus, not taking into account the rebar will provide a great convenience during the modeling stage. In addition, linear and nonlinear dynamic analyzes were performed on the reinforced and unreinforced finite element models of the bridge using the effective earthquake acceleration record of the Erzincan earthquake of 1992 and structural behavior was evaluated. The results are presented in comparison with the graphs and tables in this paper.
https://doi.org/10.31462/jseam.2020.01001017
Muhammet Karaton
Kağan Çanakçı
Micro, simplified micro and macro modelling are used for the numerical modeling of the masonry. In this study, the efficiency of a 3-dimensional fixed smeared crack model in the micro modelling of masonry walls is investigated. For this purpose, the experimental results of the masonry walls called as the JD6 and JD7 Eindhoven walls are selected. The concrete model with three parameters which special case of William Warnke model is used to calculate the nonlinear behavior of mortar and brick regions of this wall. Interface element is not use at between brick and mortar. Predictor-corrector technique used for nonlinear analysis. Numerical and experimental results are compared in terms of the base shear-peak displacement curve and the crack regions obtained in the walls. Good approximation are obtained between experimental and numerical results with regard to ultimate base-shear force obtained. Some differences are determined between experimental and numerical results with regard to threshold displacement value that calculated versus ultimate base-shear force.
https://doi.org/10.31462/jseam.2020.01018024
Emre Alpaslan
Zeki Karaca
This study aims to investigate the dynamic behavior of a one-span historical masonry arch bridge. For this reason, the masonry bridge with 15.5m in length and 4.75m in width was chosen and the modal parameters were obtained by performing numerical analyses and experimental measurements. Operational Modal Analysis technique is utilized for experimental study to determine modal parameters of the historical masonry bridge. Sensitive three-axial accelerometers were located on critical points on the bridge span and signals originated by accelerometers were collected to quantify the vibratory response of the historical bridge. The Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification method are employed to identify the natural frequencies, mode shapes, and damping ratios experimentally. The 3D finite element modeling of the historical masonry bridge was created and the natural frequencies and mode shapes of the bridge were determined numerically. Experimental results were compared with those of the finite element analysis of the bridge. It can be noticed significant differences when comparing the results of the experimental and numerical with the initial conditions. Therefore, the finite element model is calibrated by using the response surface method according to the experimental results to minimize the uncertain finite
element modeling parameters of the historical masonry arc bridge such as material properties and boundary conditions. At the end of the calibration process, the maximum differences between natural frequencies obtained experimental measurements and numerical analysis decreases from 4%-50% to 0.5%-2.5%. The final calibrated finite element model for the masonry bridge is able to produce natural frequencies in close agreement with the measured ones.
https://doi.org/10.31462/jseam.2020.01025040
Hakkı Eşki
Baris Sayin
Baris Gunes
Considering the vertical- and lateral-effects to RC buildings are exposed, type of construction and geometrical properties of the bearing members is known as the effective parameters in the structural behavior. Slabs defined the bearing members are plane members that transfer the acting loads to the columns and beams. RC slabs are generally classified as beam slab, flat slab and ribbed slab according to the way of transferring the loads in RC buildings under seismic effects. Especially in housing types, ribbed slab system is preferred, while parking type structures are used flat slab system. In this choice, the function of the structure is taken into consideration, and the effect of the selected slab type on the seismic behavior of structures can be ignored. In this respect, the structural behavior of the slab types on the structural behavior must be investigated, extensively. The aim of this study is to examine the effects of slab type on structural behavior in a low-rise RC building. Within the scope of the study, three-dimensional structural model of the examined building is prepared by considering three different slab types, and then analyzed by using linear and nonlinear-analysis methods such as equivalent earthquake load-, mode superposition- and time history analysis-method. As a result of numerical analysis, the parameters that are effective in the structural behavior and construction process – seismic performance, torsional behavior, story drift, etc.– are compared and evaluated the parameters in the selection of slab type in low-rise buildings. Consequently, suggestions for determining the most suitable slab system for the low-rise buildings presented.
https://doi.org/10.31462/jseam.2020.01041048
Özgür Avşar
Seismic design codes limit the inter-story drifts of buildings to protect the non-structural components and to minimize the secondary effects of gravity loads. A new version of Turkish Building Earthquake Code (TBEC, 2018) is in act starting from 2019 by replacing the former version of the Turkish Earthquake Code (TEC, 2007). One of the significant changes in TBEC (2018) is the definition of the inter-story drift ratio (ISDR) limit. The ISDR is limited by 2% as per TEC (2007) without considering any other criteria. However,
the ISDR limit of TBEC (2018) is modified by considering several parameters. The type of building (reinforced concrete (RC) or steel), the interaction of infill walls with the neighbouring structural components and the ratio of spectral ordinates at the fundamental period of the building of 72-year return period earthquake to 475-year return period earthquake (λ) are the three important parameters. Moreover, effective rigidities of RC members should be adopted in TBEC (2018). Change in ISDR demands and corresponding limits specified by the two versions of the earthquake code are examined for a 6-story RC building. Moreover, the variation in the ratio of spectral ordinates (λ) and ISDR limit are investigated for 105 points mainly in the Marmara Region. The comparisons are conducted for five different local site conditions (ZA to ZE). The change in the ISDR limits is considerable, especially for the poor soil conditions. Moreover, the interaction of infill walls with the structural components has a direct influence on the ISDR limits.
https://doi.org/10.31462/jseam.2020.01049060