Abstract
The objective of the study is to investigate the effects of model calibration on seismic behaviour of a historical mosque which is one of the most significant Ottomon structures. Seismic analyses of calibrated and noncalibrated numeric models were carried out by using acceleration records of Kocaeli earthquake in 1999. In numerical analysis, existing crack zones on real structure was investigated in detail. As a result of analyses, maximum stresses and displacements of calibrated and noncalibrated numerical models were compared each other. Consequently, seismic behaviour and damage state of historical masonry Hafsa Sultan mosque was determined as more realistic in the event of a severe earthquake.
Key Words
historical masonry structure; operational modal analysis; seismic analysis; time history; seismic safety
Address
Ali Demir, Halil Nohutcu and Gokhan Altintas: Department of Civil Engineering, Celal Bayar University, Manisa, Turkey
Emre Ercan: Department of Civil Engineering, Ege University, Izmir, Turkey
Emin Hokelekli: Department of Civil Engineering, Bartin University, Bartin, Turkey
Abstract
Design of safe structures with resistance to progressive collapse is of paramount importance in structural engineering. In this paper, an efficient optimization technique is used for optimal design of steel moment frames subjected to progressive collapse. Seismic design specifications of AISC-LRFD code together with progressive collapse provisions of UFC are considered as the optimization constraints. Linear static, nonlinear static and nonlinear dynamic analysis procedures of alternate path method of UFC are considered in design process. Three design examples are solved and the results are discussed. Results show that frames, which are designed solely considering the AISC-LRFD limitations, cannot resist progressive collapse, in terms of UFC requirements. Moreover, although the linear static analysis procedure needs the least computational cost with compared to the other two procedures, is the most conservative one and results in heaviest frame designs against progressive collapse. By comparing the results of this work with those reported in literature, it is also shown that the optimization technique used in this paper significantly reduces the required computational effort for design. In addition, the effect of the use of connections with high
plastic rotational capacity is investigated, whose results show that lighter designs with resistance to progressive collapse can be obtained by using Side Plate connections in steel frames.
Abstract
Due to its relatively good safety performance and aesthetic benefits, laminated glass (LG) is
increasingly being used as load-carrying members in modern buildings. This paper presents an experimental study into one applicational scenario of structural LG subjected to in-plane bending. The aim of the study is to reveal the in-plane behaviors of the LG beams made up of multi-layered glass sheets. The LG specimens respectively consisted of two, three and four plies of glass, bonded together by two prominent adhesives. A total of 26 tests were carried out. From these tests, the structural behaviors in terms of flexural stiffness, load resistance and post-breakage strength were studied in detail, whilst considering the influence of interlayer type, cross-sectional interlayer percentage and presence of shear forces. Based on the test results, analytical suggestions were made, failure modes were identified, corresponding failure mechanisms were discussed, and a rational engineering model was proposed to predict the post-breakage strength of the LG beams. The results obtained are expected to provide useful information for academic and engineering professionals in the
analysis and design of LG beams bending in-plane.
Address
Xiaokun Huang, Qiang Liu and Gang Liu: China Academy of Building Research, Beijing, China
Zhen Zhou: Kuraray (Shanghai) Co. Inc., China
Gang Li: Fuxin Special Glass Co. Inc., China
Abstract
This study tries to examine the effect of different parameters on stress analysis of infinite plates with central quasi-triangular cutout using particle swarm optimization (PSO) algorithm and also an attempt has been made to introduce general optimum parameters in order to achieve the minimum amount of stress concentration around this type of cutout on isotropic and orthotropic plates. Basis of the presented method is expansion of analytical method conducted by Lekhnitskii for circular and elliptical cutouts. Design variables
in this study include fiber angle, load angle, curvature radius of the corner of the cutout, rotation angle of the cutout and at last material of the plate. Also, diagrams of convergence and duration time of the desired problem are compared with Simulated Annealing algorithm. Conducted comparison is indicative of appropriateness of this method in optimization of the plates. Finite element numerical solution is employed to examine the results of present analytical solution. Overlap of the results of the two methods confirms the validity of the presented solution. Results show that by selecting the aforementioned parameters properly, less amounts of stress can be achieved around the cutout leading to an increase in load-bearing capacity of the structure.
Address
Mohammad Jafari, Seyed A. Mahmodzade Hoseynia and Mohammad H. Bayati Chaleshtari: Department of Mechanical Engineering, Shahrood University of Technology, Shahrood, P.O.B. 3619995161 Shahrood, Iran
Abstract
In deep open pit mines, slope stability is very important. Particularly, increasing the depths increase the risks in mines having weak rock mass. Blasting operations in this type of open pits may have a negative impact on slope stability. Several or combination of methods can be used in order to enable better analysis in this type of deep open-pit mines. Numerical modeling is one of these options. Many complex problems can be integrated into numerical methods at the same time and analysis, solutions can be performed on a single model. Rock failure criterions and rock models are used in numerical modeling. Hoek-Brown and Mohr-Coulomb terms are the two most commonly used rock failure conditions. In this study, mine planning and discontinuity conditions of a lignite mine facing two big landslides previously, has been investigated. Moreover, the presence of some damage before starting the study was identified in surrounding structures. The primary research of this study is on slope study. In slope stability analysis, numerical modeling methods with Hoek-Brown and Mohr-Coulomb failure criterions were used separately. Preparing the input data to the numerical model, the outcomes of patented-blast vibration minimization method, developed by co-author was used. The analysis showed that, the model prepared by applying Hoek-Brown failure criterion, failed in the stage of 10. However, the model prepared by using Mohr-Coulomb failure criterion did not fail even in the stage 17. Examining the full research field, there has been ongoing production in this mine without any failure and damage to surface structures.
Key Words
numerical modeling; controlled blasting; yielding criteria; deep open pit; slope stability
Address
Cemalettin O. Aksoy: Department of Mining Engineering, DokuzEylul University, Faculty of Engineering, İzmir, Turkey
Guzin G. Uyar and Yilmaz Ozcelik: Department of Mining Engineering, Hacettepe University, Faculty of Engineering, Ankara, Turkey
Abstract
In this paper, experimental as well as numerical analysis of Glass Fiber Reinforced Polymer (GFRP) laminated composite has been presented under ballistic impact with varying projectile nose shapes (conical, ogival and spherical) and incidence velocities. The experimental impact tests on GFRP composite plate reinforced with woven glass fiber (0o/90o)s are performed by using pneumatic gun. A three dimensional finite element model is developed in AUTODYN hydro code to validate the experimental results and to study the ballistic perforation characteristic of the target with different parametric variations. The influence of projectile nose shapes, plate thickness and incidence velocity on the variation of residual velocity, ballistic limit, contact force-time histories, energy absorption, damage pattern and damage area in the composite target have been studied. The material characterization of GFRP composite is carried out as required for the progressive damage analysis of composite. The numerical results from the present FE model in terms of residual velocity, absorbed energy, damage pattern and damage area are having close agreement with the results from the experimental impact tests.
Key Words
GFRP composite; ballistic impact; finite element analyses; projectile nose shape; damage analysis
Address
Md. Muslim Ansari and Anupam Chakrabartia: Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee-247667, India
Abstract
Helidecks are vital structures that act as a last exit in an emergency. They transport people and goods to and from ships and offshore plants. When designing the structure of a helideck, it is necessary to comply with loading conditions and design parameters specified in existing professional design standards and regulations. In the present study, finite element analysis (FEA) was conducted with regard to a steel helideck mounted on the upper deck of a ship considering the emergency landing of the helicopter. The superstructure and substructure were designed, and the influence of various design parameters was analyzed on the basis of the FEA results.
Key Words
helideck; offshore structure; structural design; parametric study; finite element analysis
Address
Doo-Hwan Park, Jeong-Hyeon Kim, Myung-Hyun Kim and Jae-Myung Lee: Department of Naval Architecture and Ocean Engineering, Pusan National University, Busan 609-735, Republic of Korea
Yong-Jun Park: Shipbuilding Division, Hyundai Heavy Industries, Co., Ltd., Ulsan 682-792, Republic of Korea
Jun-Hwan Jeon: Marine Research Institutes, Samsung Heavy Industries, Co., Ltd., Sungnam 463-400, Republic of Korea
Abstract
A new structural damage index for seismic fragility analysis of reinforced concrete columns is developed based on a local tensile damage variable of the Lee and Fenves plastic-damage model. The proposed damage index is formulated from the nonlinear regression of experimental column test data. In contrast to the response-based damage index, the proposed damage index is well-defined in the form of a single monotonically-increasing function of the volume weighted average of local damage distribution, and provides the necessary computability and objectivity. It is shown that the present damage index can be appropriately zoned to be used in seismic fragility analysis. An application example in the computational seismic fragility evaluation of reinforced concrete columns validates the effectiveness of the proposed damage index.
Key Words
damage index; plastic-damage model; local damage variable; seismic fragility analysis; reinforced concrete column
Address
Jun Won Kang: Department of Civil Engineering, Hongik University, Seoul, 04066, Korea
Jeeho Lee: Department of Civil and Environmental Engineering, Dongguk University, Seoul, 04620, Korea
Abstract
The beam structure with breathing cracks subjected to harmonic excitations was modeled by FEM based on Euler-Bernoulli theory, and a piecewise dynamical system was deduced. The precise integration method (PIM) was employed to propose an algorithm for analyzing the dynamic responses of the deduced system. This system was first divided into linear sub-systems, between which there are switching
points resulted from the breathing cracks. The inhomogeneous terms due to the external excitations were tackled by introducing auxiliary variables to express the harmonic functions, hence the sub-systems are homogeneous. The PIM was then applied to solve the homogeneous sub-systems one by one. During the procedures, a predictor-corrector algorithm was presented to determine the switching points accurately. The presented method can provide solutions with an accuracy to a magnitude of 10-12 compared with exact solutions obtained by the theories of ordinary differential equations. The PIM results are much more accurate than Newmark ones with the same time step. Moreover, it is found that the PIM can maintain a high level of accuracy even when the time step increases within a relatively wide range.
Key Words
beam; breathing crack; precise integration method; switching point
Address
C.C. Cui, X.S. He, Z.R. Lu, Y.M. Chen and J.K. Liu: Department of Mechanics, Sun Yat-sen University, Xingang Road West 135, 510275 Guangzhou, China
Abstract
To study the effect of looseness on mechanical behavior of dovetail mortise-tenon joints, five dovetail mortise-tenon joints, including one intact joint and four loose joints, were fabricated and tested under
cycle lateral loadings, and non-linear finite element models using the software ABAQUS were also developed. The effects of looseness on stress distribution, rotational stiffness and bearing capacity of joints were studied based on the analysis of test and simulation results. The results indicate that the hysteretic loops are anti-Z-shaped and present typical characteristics of pinching and slippage, the envelop curves of joints are classified as following two stages: elastic and strengthening stage. The peak stress, rotational stiffness and bearing capacity of joints were reduced due to looseness. The moment-rotation theoretical model of intact joint was simplified in terms of the relation of construction dimensions for buildings, and the moment-rotation theoretical model considering the effect of looseness was proposed and validated.
Key Words
traditional timber building; dovetail mortise-tenon joint; looseness; finite element analysis; theoretical model
Address
Yizhu Li, Shuangyin Cao: Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, Southeast University, Nanjing, P.R. China; School of Civil Engineering, Southeast University, Nanjing, P.R. China
Jianyang Xue: School of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an, P.R. China
