Soil-pile interaction effects in wharf structures under lateral loads

Bilge Doran,Aytuğ Seçkin 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.2

Wharfs are essential to shipping and support very large gravity loads on both a short-term and long-term basis which cause quite large seismic internal forces. Therefore, these structures are vulnerable to seismic activities. As they are supported on vertical and/or batter piles, soil-pile interaction effects under earthquake events have a great importance in seismic resistance which is not yet fully understood. Seismic design codes have become more stringent and suggest the use of new design methods, such as Performance Based Design principles. According to Turkish Code for Coastal and Port Structures (TCCS 2008), theinteraction between soil and pile should somehow be considered in the nonlinear analysis in an accurate manner. This study aims to explore the lateral load carrying capacity of recently designed wharf structures considering soil-pile interaction effects for different soil conditions. For this purpose, nonlinear structure analysis according to TCCS (2008) has been performed comparing simplified and detailed modeling results.

Soil-pile interaction effects in wharf structures under lateral loads

Doran, Bilge,Seckin, Aytug Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.2

Wharfs are essential to shipping and support very large gravity loads on both a short-term and long-term basis which cause quite large seismic internal forces. Therefore, these structures are vulnerable to seismic activities. As they are supported on vertical and/or batter piles, soil-pile interaction effects under earthquake events have a great importance in seismic resistance which is not yet fully understood. Seismic design codes have become more stringent and suggest the use of new design methods, such as Performance Based Design principles. According to Turkish Code for Coastal and Port Structures (TCCS 2008), the interaction between soil and pile should somehow be considered in the nonlinear analysis in an accurate manner. This study aims to explore the lateral load carrying capacity of recently designed wharf structures considering soil-pile interaction effects for different soil conditions. For this purpose, nonlinear structure analysis according to TCCS (2008) has been performed comparing simplified and detailed modeling results.

Interval finite element analysis of masonry-infilled walls

Erdolen, Ayse,Doran, Bilge Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.1

This paper strongly addresses to the problem of the mechanical systems in which parameters are uncertain and bounded. Interval calculation is used to find sharp bounds of the structural parameters for infilled frame system modeled with finite element method. Infill walls are generally treated as non-structural elements considerably to improve the lateral stiffness, strength and ductility of the structure together with the frame elements. Because of their complex nature, they are often neglected in the analytical model of building structures. However, in seismic design, ignoring the effect of infill wall in a numerical model does not accurately simulate the physical behavior. In this context, there are still some uncertainties in mechanical and also geometrical properties in the analysis and design procedure of infill walls. Structural uncertainties can be studied with a finite element formulation to determine sharp bounds of the structural parameters such as wall thickness and Young's modulus. In order to accomplish this sharp solution as much as possible, interval finite element approach can be considered, too. The structural parameters can be considered as interval variables by using the interval number, thus the structural stiffness matrix may be divided into the product of two parts which correspond to the interval values and the deterministic value.

Interval finite element analysis of masonry-infilled walls

Ayse Erdolen,Bilge Doran 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.1

This paper strongly addresses to the problem of the mechanical systems in which parameters are uncertain and bounded. Interval calculation is used to find sharp bounds of the structural parameters for infilled frame system modeled with finite element method. Infill walls are generally treated as nonstructural elements considerably to improve the lateral stiffness, strength and ductility of the structure together with the frame elements. Because of their complex nature, they are often neglected in the analytical model of building structures. However, in seismic design, ignoring the effect of infill wall in a numerical model does not accurately simulate the physical behavior. In this context, there are still some uncertainties in mechanical and also geometrical properties in the analysis and design procedure of infill walls. Structural uncertainties can be studied with a finite element formulation to determine sharp bounds of the structural parameters such as wall thickness and Young's modulus. In order to accomplish this sharp solution as much as possible, interval finite element approach can be considered, too. The structural parameters can be considered as interval variables by using the interval number, thus the structural stiffness matrix may be divided into the product of two parts which correspond to the interval values and the deterministic value.

Elastoplastic Finite Element Analysis of Masonry Shear Walls

H. Orhun Koksal,Bilge Doran,A. Osman Kuruscu,Ali Kocak 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.2

Masonry is the most important construction material in Turkey. It has been used for public and residential buildings in the past several thousand years. A great number of well-preserved old masonry structures still exist proving that this form of construction can successfully resist loads and environmental impact. Traditionally, most major buildings were solid walled structures with the walls bearing directly on the ground. Engineers work hard to convert the highly indeterminate, ambiguous and nonlinear behavior of historic masonry construction into something which can be understood with mathematical certainty. Therefore, practical and accurate structural analysis techniques are needed for the preserve the historical monuments as a huge cultural heritage. This paper is focused on Nonlinear Finite Element (NLFE) modeling of masonry shear walls at a macro-level taking the geometric arrangement of constituents. In this study, 3D elasto-plastic Finite Element (FE) analysis for the masonry walls that subjected to the combinations of vertical and lateral loads, are determined to find a practical method. An original meshing procedure is introduced to consider the orthotropy along the two natural directions of the masonry while the material is still assumed to be isotropic. The paper further examines parameter studies carried out to show that the relation suggested for cohesion values of mortar joint masonry can also be adopted for the masonry walls with dry joints employing compressive stresses on the top surface of the wall despite using its compressive strength. The accuracy of the proposed approach is verified by simulating a series of experiments reported in the literature. Those papers include shear tests on masonry walls with both dry and mortar joints by Raijmakers and Vermeltfoort, Oliveira and Roca. Comparisons between the predicted and measured failure loads of the walls confirm that it is possible to reproduce the fundamental features of masonry shear walls with the proposed meshing scheme. Finally, the proposed approach is shown to fit quite well the experimental load-deformation plots of masonry walls with both dry- and mortar joint under shearcompression fracture.

Computational material modeling of masonry walls strengthened with fiber reinforced polymers

Koksal, H. Orhun,Jafarov, Oktay,Doran, Bilge,Aktan, Selen,Karakoc, Cengiz Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.5

This paper aims to develop a practical approach to modeling of fiber reinforced polymers (FRP) strengthened masonry panels. The main objective is to provide suitable relations for the material characterization of the masonry constituents so that the finite element applications of elasto-plastic theory achieves a close fit to the experimental load-displacement diagrams of the walls subjected to in-plane shear and compression. Two relations proposed for masonry columns confined with FRP are adjusted for the cohesion and the internal friction angle of both units and mortar. Relating the mechanical parameters to the uniaxial compression strength and the hydrostatic pressure acting over the wall surface, the effects of major and intermediate principal stresses ${\sigma}_1$ and ${\sigma}_2$ on the yielding and the shape of the deviatoric section are then reflected into the analyses. Performing nonlinear finite element analyses (NLFEA) for the three walls tested in two different studies, their stress-strain response and failure modes are eventually evaluated through the comparisons with the experimental behavior.

Computational material modeling of masonry walls strengthened with fiber reinforced polymers

H. Orhun Köksal,Oktay Jafarov,Bilge Doran,Selen Aktan,Cengiz Karakoç 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.5

This paper aims to develop a practical approach to modeling of fiber reinforced polymers (FRP) strengthened masonry panels. The main objective is to provide suitable relations for the material characterization of the masonry constituents so that the finite element applications of elasto-plastic theory achieves a close fit to the experimental load-displacement diagrams of the walls subjected to in-plane shear and compression. Two relations proposed for masonry columns confined with FRP are adjusted for the cohesion and the internal friction angle of both units and mortar. Relating the mechanical parameters to the uniaxial compression strength and the hydrostatic pressure acting over the wall surface, the effects of major and intermediate principal stresses σ1 and σ2 on the yielding and the shape of the deviatoric section are then reflected into the analyses. Performing nonlinear finite element analyses (NLFEA) for the three walls tested in two different studies, their stress-strain response and failure modes are eventually evaluated through the comparisons with the experimental behavior.

Seismic Axial Loads in Steel Moment Resisting Frames

Jay Shen,Bulent Akbas,Onur Seker,Bilge Doran,Rou Wen,Eren Uckan 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.2

During the 1994 Northridge Earthquake, many buildings with modern steel moment resisting frames (SMRFs) suffered from connection failures. One year later, similar damage has occurred in the 1995 Kobe earthquake in Japan. The unexpected seismic response of SMRFs resulted in comprehensive analytical and theoretical investigations and major changes in steel building design have been implemented consequently. One of the requirements in the subsequent seismic design codes is the stability check of the columns. Column yielding in a seismic force resisting systems (SFRSs) is not the desired damage mode and might result in column rupture or global buckling and threaten life safety. This study focuses on exploring the seismic axial loads for columns in SMRFs under strong ground motions. For this purpose, the increase in axial loads in low-, medium-, and high-rise SMRFs are investigated at the maximum lateral load level and the corresponding lateral displacement. The results are presented in terms of PHRs, average system overstrength factors (Ωo) of all columns in the frames under the selected ground motions, the distribution of Ωo in the individual columns in the frame, and axial load levels in columns. The results indicate that axial load level remains below 0.4 in the columns for low- and medium-rise frames, whereas it may get as high as 0.95 in highrise frames.

An Experimental Investigation on Flexural Behavior of RC Beams Strengthened with Different Techniques

M. Mustafa Önal,Bas¸ak Zengin,Ali Koçak,Bilge Doran 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.7

In in many earthquake-prone regions and countries including Mediterranean area, India, the Middle East, Southeast Asia, existing buildings with its structural elements such as Reinforced Concrete (RC) beams and columns, which show little ductility, have consistently exhibited poor performance during past earthquakes and consequently unavoidable earthquake damages on these structures led to a significant loss of world cultural heritage. Therefore, appropriate strengthening techniques have to be implemented in order to improve load carrying capacities and overall ductility. This paper summarizes experimental investigations of damaged and undamaged RC beams. In this context, twenty-seven beams were tested under combined bending and shear. Eighteen RC beams were damaged and then strengthened with four different methods while nine were kept undamaged. The behavior of damaged and undamaged RC beams is discussed with emphasis on the load deflection and strain characteristics. The results indicate that the specimens strengthened with full jacketing had slightly higher load carrying capacity than the reference beams strengthened with other techniques. The experimental results can also be used for understanding the most convenient strengthened technique for damaged beams.