Challenge Journal of Structural Mechanics

42-47

Authors: Mehmet Semih Yücemen, Çetin Yılmaz

A probabilistic model is developed for the assessment of the earthquake insurance premium rates for the structures taking place in the Bolu Mountain Crossing in the Gumusova-Gerede Motorway Section. The model requires two types of studies, namely: seismic hazard analysis and estimation of potential damage to structures. The computations are carried out according to the proposed model by using the seismic hazard results obtained from the time-dependent renewal model and the best estimate damage probability matrices developed in the study.

59-64

Authors: Kemal Hacıefendioğlu, Mehmet Akköse, Alemdar Bayraktar, Ali Aydın Dumanoğlu

The effect of the non-linear material behavior of a rock-fill dam subjected to random loads is investigated by the equivalent linear method that considers the non-linear variation of soil shear moduli and damping ratios as a function of shear strain. The Keban dam constructed in Elazığ, Turkey is chosen as a numerical example. The interaction of the rock-fill dam with the reservoir is neglected, but not the foundation rock. The properties of the dam materials were taken from the dam project and assumed to be isotropic in the analysis. A stationary and ergodicity assumption are made for stochastic dynamic analysis. The E-W component of the Erzincan earthquake recorded on March 13, 1992, Erzincan, Turkey is chosen as a ground motion since it occurred nearby the dam site. The component considered is applied to the dam in the horizontal direction. The non-linear stochastic responses of the Keban dam are compared to its linear stochastic and deterministic response.

71-77

Authors: Daniel Bobos, Zeno Iosif Praisach, Doina Frunzăverde, Gilbert Rainer Gillich, Ionica Negru

Corrosion, as the spontaneous process of material degradation produced by the environment, affects the reliability and safety of structures, both by reducing the section of the components, due to material loss and by diminution of the materials mechanical strength. The authors have found a mathematical relation between discontinuities in beams and changes of its natural frequencies and developed a method to identify these discontinuities. The present paper considers the more complex case of damage determined by corrosion, where beam thinning is accompanied by mass decrease. These impose considering natural frequency changes in both directions: decrease due damage and increase because of mass loss. FEM simulations and analytical investigations were carried out, in order to find the relation between mass change in different positions along the beam and the frequency increase. The results were correlated with the “classical” relation describing frequency decrease because of discontinuities. Finally, the authors developed a new relation, proper to be used for damage produced by severe corrosion, which was validated by laboratory experiments.

84-89

Authors: Sıddık Şener, Yasin Çağlar, Mehmet Akif Benzer, Kadir Can Şener

Vertical displacement of the Korror-Babeldaop (KB) Bridge in Palau is presented. This bridge was built in 1977 by the cantilever method and collapsed 3 months after remedial prestressing in 1996. KB Bridge was a segmental prestressed concrete girder having the world record of 241 m and maximum girder depth of 14.17 m. The final mid-span deflection was in design expected to be 0.53 to 0.65 m but after 18 years it reached 1.39 m and was still increasing. With a very limited amount of official information of the bridge was available and bridge was analyzed by ANSYS finite element program. Presented is an accurate analysis using 5392 hexahedral three-dimensional (3D) finite elements with 9614 nodes by ANSYS. Hognestad concrete model and Solid 65 element type were considered. The actual vertical displacements of free end of the cantilever bridge under truck loading were compared with the 3D finite element analyses results in order to come up with a benchmark model. The collapse reasons of KB Bridge were discussed.

1-8

Authors: A. Ghani Razaqpur, Francesco Bencardino, Lidia Rizzuti, Giuseppe Spadea

The capacity provisions of conventional Reinforced Concrete (RC) and Prestressed Concrete (PC) beams subjected to combined action of torsion, shear and flexure are well known and stated by international/national codes. Similar provisions lack for concrete members containing Fibre Reinforced Polymer (FRP) reinforcements. In general, there is paucity of research on the treatment of torsion combined with other stress resultants for FRP-RC/PC members. In this paper the theoretical method proposed by the Canadian standard CSA S806 for FRP-RC/PC structures is presented. The critical issues, related to this topic, such as the appropriate strength and inclination of the diagonal struts and failure criteria are critically analyzed and addressed. In order to assess the reliability of this study a comparison between available experimental data regarding FRP-RC/PC beams subjected to combined actions and their corresponding theoretical provisions derived by the CSA S806 standard is shown. Furthermore, another approach, available in literature, which is based on the space truss model, is examined and used for comparison in order to evaluate the theoretical provisions offered by this model against the tests value of the set of the beams analyzed in this study. Based on the critical analysis of the results, it can be highlighted that the CSA method is able to conservatively predict the capacity of these beams.

13-17

Authors: Hisato Hotta, Takeshi Nakajima

Partial walls separated from columns are generally treated as nonstructural elements because their behavior aren’t analyzed much. Partial walls jointed rigidly to RC frames raise horizontal load-carrying capacity, however they may give an influence on RC frames when they fall in brittle failure. Objective of this paper is to clarify the influence of partial walls falling in shear failure on RC frames through a static loading test and a shaking table test. The experiment shows that, after one of the partial walls fails, story drift rapidly increases. It shows progress of flexural deformation at one end of columns, and it may cause story collapse. The result is obtained from both loading tests.

22-26

Authors: Farzad Hejazi, Jamalodin Noorzaei, Abang Abdullah Abang Ali, Mohd Saleh Jaafar

Various types of interlocking mortarless (dry-stacked) block masonry systems have been developed worldwide. However, the characteristics of dry joints under compressive load, and their effect on the overall behavior of the interlocking mortarless system, are still not well understood. This paper presents an investigation into the dry-joint contact behavior of masonry and the behavior of interlocking mortarless hollow blocks wall construction subjected to seismic excitation. In the system developed, the blocks are stacked on one another and three-dimensional interlocking protrusions are provided in the blocks to integrate the blocks into walls. The response of the mortarless hollow block wall with respect to acceleration displacement and stress have been discussed.

32-37

Authors: Turgut Öztürk, Zübeyde Öztürk, Onur Öztürk

Earthquakes are one of the most important and hazardous natural disasters in the world and in our country. They also have lots of characteristics from the point of effects caused by them. For this reason it requires special engineering approach to analyze those effects and to design earthquake resistant structures. Almost all of the life losses caused by the earthquakes are related with improperly designed buildings safety of which are not ensured against severe earthquakes. Structural damages and collapses cause very important economical losses. So, understanding of the characteristics of an earthquake and correct determination of the behavior of buildings under earthquake excitation turn out to be the most important requirement to build earthquake resistant buildings. When we take into consideration the destructive effects of severe earthquakes that happened especially in recent years (Kocaeli 1999, Düzce 1999) one can easily see the importance of knowing the behavior of buildings under earthquake loads. In this study torsional effects that occur during earthquake excitations are analyzed in multi-story reinforced concrete buildings. In that manner the behavior of reinforced concrete structures under earthquake loads are examined and by the way the behaviors of structures having torsional irregularities are enlightened and clarified. Moreover the effects of rigidity, ultimate capacity and ductility on the behavior of structures under ground motion are summarized. Torsional irregularity is a key irregularity in determination of the method to be used in earthquake analysis. Definition of the torsional irregularity of a multi-story reinforced concrete building is explained in accordance with Turkish Earthquake Code and the related principles of computations that have to be followed according to the code are given. Multi-story reinforced concrete buildings are classified according to their plan geometry and the effects of plan geometry on the torsional irregularity are explained. While in certain structures torsional irregularity may happen in very high levels in some structures it may happen so small that can be safely omitted. For that reason buildings forming torsional irregularity are classified and their characteristics and torsional irregularity parameters are given. Shear walls without causing any torsional irregularity on buildings having different plan geometries are shown.