- Mixed 3D Beam Models: Differential Equation Derivation and Finite Element Solutions
- F. Auricchio ; G. Balduzzi ; C. Lovadina
- Book Title / Journal: European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)
- Year: 2012 , Volume: , Series:
- Structural Analysis
- Keywords: Hellinger-Reissner principle ; 3D beam model ; dimensional reduction ; mixed beam finite element
- Description
- In this document we illustrate the dimensional-reduction approach applied to 3D solid elastic equations in order to obtain a beam model.
We start from the Hellinger-Reissner (HR) principle, in a formulation which guarantees the selection of a compatible solution in a family of equilibrated fields. Then, we introduce a semidiscretization within the cross-section, this allows to reduce the problem’s dimension from 3D to 1D and to formulate the beam model. After a manipulation of the 1D weak model (done in order to guarantee the selection of an axis-equilibrated solution in a family of axis-compatible fields), we introduce a discretization along the beam axis obtaining the related beam Finite Element (FE).
On one hand, the initial HR principle formulation leads to an accurate stress analysis into the cross-section, on the other hand, the 1D model manipulation leads to an accurate displacement
analysis along the beam-axis. Moreover, the manipulation allows to statically condensate
stresses out at element level, improving the numerical efficiency of the FE algorithm.
In order to illustrate the capability of the method, we consider a slim cross-section beam that shows non trivial behaviour in bending and for which the analytical solution is available in literature. Numerical results are accurate in description of both displacement and stress variables, the FE solution converges to the analytical solution, and the beam FE models complex phenomena like anticlastic bending and boundary effects.
- Abstract
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- Advanced Computational Engineering
- O. Allix ; C. Carstensen ; J. Schroder ; P. Wriggers
- Book Title / Journal: Mathematisches Forschungsinstitut Oberwolfach
- Year: 2012 , Volume: , Series: Report No. 09/2012
- Structural Analysis
- Keywords: Finite element method
- Description
- The finite element method is the established simulation tool for the numerical solution of partial differential equations in many engineering problems with many mathematical developments such as mixed finite element methods (FEMs) and other nonstandard FEMs like least-squares, nonconforming, and discontinuous Galerkin (dG) FEMs. Various aspects on this plus related topics ranging from order-reduction methods to isogeometric analysis has been discussed amongst the pariticpants form mathematics and engineering for a large range of applications.
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- Estimate of fundamental period of reinforced concrete buildings: code provisions vs. experimental measures in Victoria and Vancouver (BC, Canada)
- L. Chiauzzi ; A. Masi ; M. Mucciarelli ; J.F. Cassidy ; K. Kutyn ; J. Traber ; C. Ventura ; F. Yao
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Structural dynamics
- Keywords: Fundamental period ; reinforced concrete buildings ; ambient vibration ; Canadian buildings
- Description
- The fundamental period of a group of reinforced concrete (RC) buildings located in the cities of Victoria and Vancouver (British Columbia, Canada) has been estimated using ambient vibration data. As result a preliminary height- dependent relationship has been derived for a fully elastic condition. The regression returns very similar values respect to those obtained in other countries using the system identification technique based on ambient vibrations. As expected, the results show that building periods estimated based on simple equations provided by earthquake design codes in Europe (EC8) and North America (UBC97 and NBCC-2005) are significantly greater than the periods computed using ambient vibration records on the monitored buildings.
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- A Low Cost Retrofit Scheme for Masonry-Infilled Non-Ductile Reinforced Concrete Frames
- P. Lukkunaprasit ; J. Srechai
- Book Title / Journal: 15th World Conference on Earthquake Engineering, Portugal, Lisbon
- Year: 2012 , Volume: , Series:
- Repair and Retrofit of Structures
- Keywords: Non-Ductile Frame ; Reinforced Concrete ; Un-reinforced Masonry Infil ; seismic retrofit
- Description
- A low cost and effective scheme has been developed for retrofitting masonry-infilled reinforced concrete (RC) frames.
Three ¾ scaled models of single bay, single story non-ductile RC frames with un-reinforced masonry (URM) infill panels were tested under horizontal cyclic loading and a constant vertical load. The experimental results indicate that an un-retrofitted specimen suffers corner crushing and abrupt shear failure in the columns at a very small drift ratio of
0.50%. The retrofitted masonry panel is separated from the columns so that no shear is transferred to them. Steel brackets are provided to transfer the interactive forces between the RC frame and URM panel. The peak lateral load decreases approximately in proportion to the area reduction ratio of the panel with desirable gradual drop in capacity whereas the drift capacity increases to about 1.50%. The retrofit scheme compares favorably with others incorporating either heavy mesh reinforcement or carbon fiber reinforced polymer.
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- Evaluation of A Retrofit Solution Used for Concrete Masonry Walls with Large Openings Using FEM Nonlinear Analysis
- M. Motamedi ; H. Kakolvand ; M Yekrangnia
- Book Title / Journal: 15th World Conference on Earthquake Engineering, Lisbon, Portugal
- Year: 2012 , Volume: , Series:
- Repair and Retrofit of Structures
- Keywords: Unreinforced masonry walls ; push over analysis ; seismic retrofit ; failure mode
- Description
- This paper deals with the modeling of existing unreinforced concrete block walls with finite elements and evaluation of a proposed retrofit solutions used in practice. The objectives of developing the analytical model were prediction of inelastic response of the walls with the openings and the study of the effect of the retrofit solution for seismic upgrading of the existing walls. Concrete core technique was employed for wall retrofit of the different models. To study of in-plane behavior of the walls the models were verified with the test results obtained from the similar walls studied in previous works and calibrated to present the identical inelastic loaddeformation response of the tested specimens. Nonlinear push over analysis was performed on the models to study the capacity of the walls up to 4% drifts. As results, the inelastic response was compared in different studied walls. Lateral resistance capacity, initial stiffness and the mode of failure of the walls were presented and the effect of the retrofit solution on the behavior of the existing masonry walls with large openings was
evaluated.
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- The 29th May 2012 Emilia Romagna Earthquake
- I. Ioannou ; R. Borg ; V. Novelli ; J. Melo ; D. Alexander ; In. Kongar ; E. Verrucci ; B. Cahill ; T. Rossetto
- Book Title / Journal: EPICentre Field Observation Report
- Year: 2012 , Volume: , Series:
- Earthquake engineering ; Seismic effects
- Keywords: Emilia Romagna Earthquake
- Description
- The 5.9Mw earthquake, which hit the Emilia-Romagna region of Italy on 20th May 2012 (see Rossetto et al, 2012) was followed on the 29th May 2012 by a 5.8Mw earthquake with epicentre 15km North West of the former event. This earthquake caused further damage to locations hit by the 20th May earthquake, and extended the affected area to the East-side of the province of Modena, resulting in 17 deaths and 14,000 homeless.
A team consisting of Dr Ioanna Ioannou, Randolph Borg and Jose Melo from EPICentre, and Viviana
Novelli from University of Bath, travelled to the affected areas on 2nd June 2012. The team spent
four days in the field, re-visiting Finale Emilia, San Felice sul Panaro, San Agostino and Mirabello as
well as visiting new areas such as Mirandola, Cento, Cavezzo and San Possidonio. Rapid surveys were
conducted that focused on the overall performance of residential, commercial, industrial and historical structures, emergency management and on geotechnical features of the two recent events.
The present report complements the first reconnaissance report (Rossetto et al, 2012) and should be read in addition to it in order to obtain a complete picture of the impact of the two moderate
events. Both reports can be downloaded from the EPICentre website (www.epicentreonline.com), where kml files with the georeferenced photos collected in the field for the two events can also be
downloaded (for viewing on Google Earth).
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- Effects of Capacity Design Rules on Seismic Performance of Steel Moment Resisting Frames
- M.T. Naqash ; G. De Matteis ; A. De Luca
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: Seismic codes ; Moment resisting steel frames ; Seismic resistance ; Pushover analysis
- Description
- The current paper deals with the seismic design of 9-Storey office building using Eurocode 8 and AISC
(American Institute of Steel Construction) provisions, where the seismic load resisting system is composed of either spatial or perimeter moment resisting frames. According to EC8, Ductility Class High (DCH) and Ductility Class Medium (DCM) with behaviour factor of 6.5 and 4.0 respectively, are used. Whereas in the case of AISC code, only Special Moment resisting Frame (SMF) with response modification factor of 8 is employed.
In order to shed light on the pros and cons of the design criteria and thus the influence on the capacity design rules of the two aforementioned codes, designed frames are analysed by non-linear static analysis. The frame performances are measured in terms of overstrength and redundancy factors, strength demand to capacity and drift demand to capacity ratios, allowing interesting conclusions to be drawn.
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- Enhancement of the seismic performance of AAC masonry by means of flat-truss bed-joint reinforcement
- A. Penna ; G. Magenes ; M. Rota ; M- Mandirola
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: horizontally reinforced masonry ; cyclic tests ; displacement capacity
- Description
- Only few experimental tests are available in the literature on bed-joint reinforced load-bearing masonry. These are performed on prototypes with different masonry typologies, often reduced scale and, in any case, only for a small number of combinations of slenderness, axial load and boundary conditions. This work presents the results
of an experimental campaign including in-plane cyclic tests on autoclaved aerated concrete (AAC) masonry panels with thin bed- and head-joints filled with glue-mortar. Some of the specimens are made of unreinforced masonry, whilst in other the masonry walls are reinforced by means of bed-joint flat-truss reinforcement only. Based on the results of these tests, complemented by specific tests performed on wallettes realised with the two
different construction techniques, a possible strength criterion is proposed. The results indicate that the inclusion of bed-joint reinforcement has the double effect of improving masonry resistance and displacement capacity, hence reducing damage.
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- Design of the Unreinforced Masonry Shear Wall Resistance in the High Seismic Areas. Case Study
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- Book Title / Journal:
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: shear strength
- Description
- Because of diagonal cracking failure (due to main tensile stresses as the main failure criterion) of the unreinforced masonry shear walls subject to lateral in-plane forces and eccentric compression, it is very important to evaluate the capacity of the shear resistance and to perform the strength request verification in the critical section of the wall.
In the Romanian Codes, capacity of shear resistance of the wall (VRd) is calculated at modified ULS, by limiting tensile length zone, at eccentric compression. Although the numbers of levels are sever reduced with this method is difficult to respect the strength request.
In Romania was realized another methodology (authors: G&R Popescu), with capacity of shear resistance evaluated taking into account the principal failure by diagonal cracking, according with the materials resistance theory. The values of (VRd) are close with those obtained from tests. Case Study contains walls calculated with the two methods.
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- Inelastic Seismic Response of Reinforced Concrete Buildings with Symmetric and Unsymmetric Floor Diaphragm Openings
- M.T. Al Harash ; N. Panahshahi
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: inelastic response ; concrete buildings
- Description
- Floor and roof diaphragms play a key role in distributing earthquake-induced loads to the lateral load resisting systems. The in-plane flexibility of the diaphragms was often ignored for simplicity in practical design, until recently where building standards such as ASCE7 (2005) acknowledged that this assumption can result in considerable errors when predicting the seismic response of RC buildings with diaphragm plan aspect ratio greater than 3:1. However, the influence of floor diaphragm openings has not been directly considered. In this paper, the inelastic seismic response of five 3-story reinforced concrete buildings with end shear walls and plan
aspect ratio of 4:1 with symmetric and unsymmetric floor openings within the middle two-thirds of the building using an enhanced version of IDARC2 are presented. It is concluded that the influence of “inelastic” in-plane diaphragm deformations due to floor openings may not be overlooked when openings are present irrespective of where they are located.
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- Study on Shaking-Table Experiment of a Full-Scale Four-Story Steel Building
- T. Tuan-Nam ; K. Kasai
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Structure types ; Steel structures ; Earthquake engineering
- Keywords: E-Defense shaking-table ; numerical analysis ; collapse experiment ; local buckling ; incremental dynamic analysis
- Description
- This paper presents the dynamic collapse analysis of a full-scale four-story steel building which was
experimented to collapse at the E-Defense shaking-table in Japan, in 2007, using the ground acceleration histories recorded at the JR Takatori station during the 1995 Hyogo-ken Nanbu earthquake. Deterioration of columns on the first story level due to local buckling is thought to be one of major reasons for the building collapse. Fiber method approach is adopted in the analysis to simulate local buckling at the column ends. Hypothetical analyses estimate the collapse capacity of the building specimen at approximately 0.9 times Takatori ground motion level. The collapse capacity of the building specimen under various propagating directions of the non-scaled Takatori ground motion is also investigated, showing that the building likely collapses under any propagating direction of the ground motion.
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- Experimental Study of the Behaviour of a New Replaceable Bracing System (BBBS)
- S.V. Khonsari ; M. Moradi ; D. Zarei ; H. Farahani ; G.L. England
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Earthquake engineering
- Keywords: Structural Bracing Systems ; Replaceable Bracings ; Cyclic Loading ; Energy Dissipation ; Retrofitting
- Description
- A new bracing system with new features somewhat different from those of the existing ones was devised and is presented. These features comprise some of the advantages of eccentric bracing systems including their ability to dissipate energy through bending of flexural elements while lacking some of the disadvantages of such systems
including their inability of being replaced upon damage during events such as earthquakes, etc. While in traditional types of braces, including both concentric and eccentric ones, braces are under axial loading, in this new system they work in a bending capacity. As a result, the sort of flexibility which is introduced in the system in the presence of eccentric braces (definitely at the price of forcing the potential damage to occur and be concentrated at the girders/beams to which such braces are connected), is now provided by the braces and at the price of sacrificing them. Therefore, if the level of damage is such that the damaged element is no longer usable, the replacement of the braces is a more viable and economically justifiable than that of the girders. Moreover, since girders, as part of the deck/floor system, are normally engaged with other elements such as stringers/joists, their replacement may not be practically possible at all. Such bracing systems, called Broken Beam Bracing System (BBBS), have the potential of being used in building as well as industrial structures as originally-used
elements or in a retrofit/repair capacity.
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- Comparison of the Seismic Performance of Equivalent Straight and Curved Bridges due to Transverse Seismic Excitation
- E. Khan ; M.J. Kowalsky ; J.M. Nau
- Book Title / Journal: 15th World Conference on Earthquake Engineering
- Year: 2012 , Volume: , Series:
- Bridge management ; Bridges ; Earthquake engineering
- Keywords: Direct Displacement Based Design ; Bridges ; Transverse Seismic Design of Curved Bridge
- Description
- This study compares the transverse response of equivalent straight and curved bridges to investigate the hypothesis made by the AASHTO Guide Specification for LRFD Seismic Bridge Design that curved bridges may be analyzed as if they are straight, provided the bridge is regular. For this purpose curved bridges with subtended angles of 15, 30, 45, 60, 75, and 90 degrees, having the total arc length equal to the length of the equivalent straight bridge, are considered. Other parameters considered in this study are the number of spans
(two, four and six), and abutment restraints (9 different conditions). The equivalent straight bridges are designed using the Direct Displacement Based Design (DDBD) procedure including these parameters. The resulting designs are then analyzed with Inelastic Time History Analysis using both straight and curved geometry. Each bridge was subjected to 7 spectrum compatible time histories. Individual as well as average results are tabulated.
It is observed that deviation in the response of the curved bridge from the equivalent straight bridge increases as the subtended angles become larger and the number of spans reduces. It was also found that the type and degree of abutment restraint is a rather critical parameter in controlling the response of the bridge, the most significant being longitudinal abutment restraint which had a profound impact on results.
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- Seismic Performance Assessment of Buildings_Vol.1
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- Book Title / Journal:
- Year: 2012 , Volume: 1 , Series:
- Earthquake engineering
- Keywords: Seismic performance ; buildings
- Description
- This report describes a general methodology and recommended procedures to assess the probable seismic performance of individual buildings based on
their unique site, structural, nonstructural, and occupancy characteristics. Performance is measured in terms of the probability of incurring casualties,
repair and replacement costs, repair time, and unsafe placarding. The methodology and procedures are applicable to new or existing buildings, and
can be used to: (1) assess the probable performance of a building; (2) design new buildings to be capable of providing desired performance; or (3) design seismic upgrades for existing buildings to improve their performance.
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- Seismic Performance Assessment of buildings_Vol.2
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- Book Title / Journal:
- Year: 2012 , Volume: 2 , Series: FEMA P-58-2
- Earthquake engineering
- Keywords: seismic assessment ; buildings
- Description
- This report provides guidance on implementing the seismic performance assessment methodology set forth in FEMA P-58-1, Seismic Performance
Assessment of Buildings, Volume 1 – Methodology, to assess the seismic performance of individual buildings based on their unique site, structural,
nonstructural, and occupancy characteristics, expressed in terms of the probability of incurring casualties, repair and replacement costs, repair time, and unsafe placarding. This Implementation Guide contains examples illustrating the performance assessment process, including selected
calculation and data generation procedures, as well user manuals for selected electronic materials provided in Volume 3 – Supporting Electronic Materials and Background Documentation.
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