Kasım Armağan Korkmaz

A practical approach for nonlinear analysis of tensegrity systems

Tensegrity systems are lightweight structures composed of cables and struts. The nonlinear behavior of tensegrity systems is critical; therefore, the design of these types of structures is relatively complex. In the present study, a practical and efficient approach for geometrical nonlinear analysis of tensegrity systems is proposed. The approach is based on the point iterative method. Static equilibrium equations are given in nodes for subsystems, thus the maximum unknown displacement number in each step is three. Pre-stress forces in the system are taken into account in a tangent stiffness matrix, while similar calculations are carried out for each node in the system which has a minimum of one degree of freedom. In each iteration step, the values found in previous steps are used. When it reaches permissible tolerance of calculation, final displacements and internal forces are obtained. The structural behavior of the tensegrity systems were evaluated by the proposed method. The results show that the method can be used effectively for tensegrity systems.

Investigation of traffic-induced vibrations on masonry buildings in Turkey and countermeasures

Masonry buildings are a common low-rise residential building type in Turkey. These buildings are generally built by the owner with nonengineering background and mostly they are not well designed buildings. Traffic induced vibrations are one of the important damage reasons for these types of buildings. In the present study, masonry buildings were investigated with regard to vehicle loads. Different modeling types and conditions were employed in the analyses. Loading cases and soil conditions were investigated for determination of the structural behavior of masonry buildings. Furthermore, a passive barrier effect was investigated by considering a damping trench at a certain distance from the building surface with and without stabilization materials implanted for damping the vibrations caused by vehicles. As a result of the study, traffic induced vibrations on structural behavior of masonry buildings were found critical and the damping trench was a considerable countermeasure for that vibration.

Comparison of critical column buckling load in regression, fuzzy logic and ANN based estimations

In structural stability analyses, determining the critical buckling load is a crucial issue. Regression, fuzzy logic and Artificial Neural Network ANN algorithms can be used to determine critical buckling loads. This study compares the results of different approaches for column buckling load prediction. Regression, Fuzzy logic and ANN algorithms were employed in the analyses, representing material properties to take uncertainties into account and the results were compared. The results show that uncertainties play an important role in stability analyses and should be considered in the design. The elastic modulus results predicted by regression, fuzzy logic and ANN are also compared to those obtained using empirical results of the buildings codes and various models. These comparisons show that obtained results in the present study give closer results than the different design codes. Therefore, proposed models can be used for critical buckling loads and regression, fuzzy logic and ANN have strong potential as a feasible tool for estimating column buckling loads within the range of input parameters considered.

Investigation of structural safety of existing masonry healthcare facilities in Turkey

Masonry healthcare facilities in Turkey are investigated in the current research. The structural assessment of the healthcare facilities has become very important for increasing building safety. A large amount of the existing healthcare facilities are generally old buildings, constructed before engineering practices were developed making most buildings vulnerable to severe structural damage. Since healthcare facilities are costly buildings to replace, structural and non-structural assessments have economical importance. Even non-structural behavior can be more critical than structural behavior as ground vibrations can cause severe damage to these types of facilities. Different ground vibrations and soil types are employed in the analyses to investigate structural and non-structural behavior of these types of facilities.

Determination of elastic moduli effects on storey-drifts by fuzzy logic algorithm

Concrete compression strength is a standard input for obtaining the elastic modulus of concrete. Calculated values of elastic modulus for the same concrete strength may vary according to different codes throughout the world since the formulas of the elastic modulus are different. Elastic modulus is one of the important parameters for structural design. Storey-drifts are also among the important structural design criteria directly related to the elastic modulus. Different elastic moduli values may lead lateral storey-drift calculations to differ from the code requirements. More dependable elastic moduli definition results in more dependable storey-drift calculations. Fuzzy logic algorithm, which generates more dependable results in engineering problems, is applicable to solve this problem. This study investigates the effects of storey-drifts on structural design; upper and lower boundaries of elastic moduli are predicted using a fuzzy logic algorithm in order to determine the effects of the elastic moduli on the storey-drift limitations found in different design codes. The study considers various design codes that are obtained worldwide. Study results also show that using a range of values for the elastic moduli is a more dependable approach for structural design safety, and that dependable storey-drifts are crucially important for structural design.

Rize Merkez Kurşunlu Camisi’nin deprem davranışının incelenmesi

Tarihi yapilarin mevcut yuklere ve ileride olabilecek zorlanmalara karsi yapisal davranislarinin belirlenmesi, korunmasi, saglamlastirilmasi, restorasyon ve muhendislik acisindan oldukca onemlidir. Bu kapsamda, tarihi yapilar bilgisayar programlari ile modellenerek analizleri yapilmakta ve davranislari belirlenmektedir. Bu calismada, SAP2000 programi kullanilarak Rize Merkez’de bulunan ve 1570 yilinda Iskender Cafer Pasa tarafindan yaptirilan Kursunlu Camisi uzerinde Cape Mendocino, Duzce ve Landers depremleri uygulanarak, zaman tanim alaninda dinamik analizler gerceklestirilmistir. Yigma tasiyici sisteme sahip olan tarihi yapida her bir ivme kaydi icin ortaya cikan yer degistirme ve gerilme degerleri elde edilmis ve analiz sonuclari dogrultusunda bir degerlendirme yapilmistir.