scholarly journals Seismic Assessment of Six Typologies of Existing RC Bridges

2020 ◽  
Vol 5 (6) ◽  
pp. 52
Author(s):  
Pietro Crespi ◽  
Marco Zucca ◽  
Nicola Longarini ◽  
Nicola Giordano
Keyword(s):  
Pushover Analysis ◽  
Computational Effort ◽  
Constitutive Law ◽  
Engineering Practice ◽  
Damage Potential ◽  
Safety Level ◽  
Seismic Safety ◽  
Rc Structures ◽  
Brittle Damage ◽  
Italian Context

Over the last few decades, the attention on the safety of existing reinforced concrete (RC) structures has significantly increased. RC bridges, in particular, are highly relevant for strategic importance. In the Italian context, several of these bridges were built around 1960, when engineering practice commonly ignored or underestimated the presence of seismic actions. Therefore, it is fundamental to quantify as accurately as possible their seismic safety level with state-of-the-art analysis techniques. In this paper, an efficient procedure based on the multi-modal pushover analysis approach is proposed for the risk evaluation of several bridges of the Italian highway network. This procedure, tailored for portfolio level assessment, takes into account the non-linear behavior and the complex dynamic response this type of structure with limited computational effort. Three fundamental aspects are defined for the structural modelling of bridges, i.e., materials’ constitutive law, finite element type and nonlinear hinge models. Flexural and shear nonlinearities of piers are included to account for ductile and brittle damage potential. The standardized procedure guarantees consistent comparisons among different bridges of the same network in the form of risk indexes.

scholarly journals Evaluation of a Modified MPA Procedure Assuming Higher Modes as Elastic to Estimate Seismic Demands

2004 ◽  
Vol 20 (3) ◽  
pp. 757-778 ◽  
Author(s):  
Anil K. Chopra ◽  
Rakesh K. Goel ◽  
Chatpan Chintanapakdee
Keyword(s):  
Structural Engineering ◽  
Pushover Analysis ◽  
Computational Effort ◽  
Attractive Alternative ◽  
Engineering Practice ◽  
Seismic Demands ◽  
History Analysis ◽  
Modes Of Vibration ◽  
Response History Analysis ◽  
Damped Systems

The modal pushover analysis (MPA) procedure, which includes the contributions of all significant modes of vibration, estimates seismic demands much more accurately than current pushover procedures used in structural engineering practice. Outlined in this paper is a modified MPA (MMPA) procedure wherein the response contributions of higher vibration modes are computed by assuming the building to be linearly elastic, thus reducing the computational effort. After outlining such a modified procedure, its accuracy is evaluated for a variety of frame buildings and ground motion ensembles. Although it is not necessarily more accurate than the MPA procedure, the MMPA procedure is an attractive alternative for practical application because it leads to a larger estimate of seismic demands, improving the accuracy of the MPA results in some cases (relative to nonlinear response history analysis) and increasing their conservatism in others. However, such conservatism is unacceptably large for lightly damped systems, with damping significantly less than 5%. Thus the MMPA procedure is not recommended for such systems.

scholarly journals Energy balance analysis in non linear dynamic equivalent systems.

2018 ◽  
Vol 148 ◽  
pp. 03002
Author(s):  
Iturregui Arranz Carlos ◽  
Soria Herrera Jose Manuel ◽  
Muñoz Díaz Ivan ◽  
García Palacios Jaime Higinio
Keyword(s):  
Energy Balance ◽  
Pushover Analysis ◽  
Degree Of Freedom ◽  
Eurocode 8 ◽  
Type I ◽  
Safety Level ◽  
Rc Structures ◽  
Equivalent Damping ◽  
Nonlinear Properties ◽  
New Formulation

The aim of the paper is to present a critical analysis for nonlinear dynamic vibrations. It is applicable to single degree of freedom –SDOF- of reinforced concrete –RC- structures, revealing its multi degree of freedom –MDOF- performance, showing contrast using the balance of energy, using six accelerograms based on type I and II spectrum, according with Eurocode-8. The degradation curve was obtained applying a new formulation, based on the system work and complementary work, into the pushover analysis. A new method incorporating the Bouc-Wen-Baben-Noori theory and global damage was used for the analysis, adding relevance to the: energy balance in its dissipative part, analysis of the structure’s fundamental parameters, relation’s effective period, equivalent damping and global ductility. The powers, energies and works developed are analyzed, creating a precise balance since energy enters selectively. Hence, an equivalent damping containing a viscous and hysteretic part is predictable, accordingly to the variation of the building’s nonlinear properties. Evaluation of the adequateness and safety level are also obtainable. The controlled parameters contrasted with the balance predicts the structure’s MDOF situation, at any moment related with seismic events. This methodology can be used to stablish a systematic control of nonlinearities for other structural schemes.

A Discrete Element for Modeling Masonry Vaults

2010 ◽  
Vol 133-134 ◽  
pp. 447-452 ◽  
Author(s):  
Ivo Caliò ◽  
Francesco Cannizzaro ◽  
Massimo Marletta
Keyword(s):  
Numerical Models ◽  
Computational Cost ◽  
Discrete Element ◽  
Computational Effort ◽  
Constitutive Law ◽  
Engineering Practice ◽  
Nonlinear Behaviour ◽  
Seismic Behaviour ◽  
Historical Masonry ◽  
Macro Element

The assessment of the seismic response of historical masonry buildings represents a subject of considerable importance but, at the same time, of very difficult task. Refined finite element numerical models, able to predict the non-linear dynamic mechanical behavior and the degradation of the masonry media, require sophisticated constitutive law and a huge computational cost that makes these methods nowadays not suitable for practical application. In the past many authors developed simplified or alternative methodologies that, with a reduced computational effort, should be able to provide numerical results that can be considered sufficiently accurate for engineering practice purposes. However most of these methods are based on simplified hypotheses that make these approaches inappropriate for monumental buildings. In this paper a three dimensional discrete element model, able to predict the nonlinear behaviour of masonry shell elements, is presented as an extension of a previously introduced spatial discrete-element conceived for the simulation of both the in-plane and the out-of-plane behavior of masonry plane elements. The new macro-element enriches a larger computational framework, based on macro-element approach, devoted to the numerical simulation of the seismic behaviour of historical masonry structures.

Local Strengthening of Reinforced Concrete Structures as a Strategy for Seismic Risk Mitigation at Regional Scale

2015 ◽  
Vol 31 (2) ◽  
pp. 1083-1102 ◽  
Author(s):  
Raffaele Frascadore ◽  
Marco Di Ludovico ◽  
Andrea Prota ◽  
Gerardo Mario Verderame ◽  
Gaetano Manfredi ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Risk Mitigation ◽  
Regional Scale ◽  
Cost Effective ◽  
Seismic Capacity ◽  
Safety Level ◽  
Seismic Safety ◽  
Rc Structures ◽  
2009 L’Aquila Earthquake ◽  
Recent Earthquakes

Recent earthquakes have clearly shown the high vulnerability of existing reinforced concrete (RC) structures. There is a crucial need to find cost-effective and efficient strategies and methods to strengthen a large number of buildings (i.e., at a regional scale) before future major earthquakes occur. A viable strategy to prevent potential damage caused by earthquakes could be to selectively upgrade local capacity of individual structural components. In the aftermath of the 6 April 2009 L'Aquila earthquake, local retrofit work based on the use of fiber polymer reinforcement (FRP) were executed to increase the seismic capacity of lightly damaged public and private buildings. According to theoretical analyses carried out on six reinforced concrete (RC) school buildings in L'Aquila, a seismic safety level of about 60% of that requested in the design of a new building can be achieved in most cases by FRP-based strengthening of exterior joints.

Pushover Analysis Based on Equivalent Diagonal Springs for the Assessment of the Seismic Safety of Post-and-Beam Timber Buildings Braced with Nailed Shear Walls

2017 ◽  
Vol 755 ◽  
pp. 170-180
Author(s):  
Natalino Gattesco ◽  
Ingrid Boem
Keyword(s):  
Static Analysis ◽  
Pushover Analysis ◽  
Shear Walls ◽  
Nonlinear Static Analysis ◽  
Plastic Behavior ◽  
Ground Acceleration ◽  
Good Reliability ◽  
Equivalent Viscous Damping ◽  
Seismic Safety ◽  
Capacity Spectrum

A method for a simplified modeling of post-and-beam timber buildings braced with nailed shear walls, useful for seismic design purposes, is presented and discussed in the paper. This strategy is based on the schematization of the vertical diaphragms through equivalent diagonal springs with elastic-plastic behavior and allows the assessment of the resisting ground acceleration by performing nonlinear static analysis; the Capacity Spectrum method based on equivalent viscous damping was applied. This nonlinear procedure constitutes a reliable and simple alternative to the linear static analysis using the behavior factor q. The procedures to determine the characteristics of the equivalent elements (stiffness and load-carrying capacity) are based on analytical evaluations, starting from the actual characteristic of shear walls. A comparison between the results of numerical simulation based of more refined and complex models, previously presented by the authors, and this time-reducing, simplified analysis proved the good reliability of the method.

PUSHOVER ANALYSIS BY ONE ELEMENT PER MEMBER FOR PERFORMANCE-BASED SEISMIC DESIGN

2010 ◽  
Vol 10 (01) ◽  
pp. 111-126 ◽  
Author(s):  
S. W. LIU ◽  
Y. P. LIU ◽  
S. L. CHAN
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Pushover Analysis ◽  
Nonlinear Behavior ◽  
Computational Effort ◽  
Effective Length ◽  
Single Element ◽  
Individual Element ◽  
Economical Design ◽  
Performance Based Seismic Design

Nonlinear static (pushover) analysis is an effective and simple tool for evaluating the seismic response of structures and offers an attractive choice for the performance-based design. As such, it has generally been used in modern design due to its practicality. However, the nonlinear plastic design method consumes extensive computational effort for practical structures under numerous load cases. Thus, an efficient element capturing the nonlinear behavior of a beam-column will be useful. In this paper, the authors propose a practical pushover analysis procedure using a single element per member for seismic design. As an improvement to previous research works, both P – Δ and P – δ effects as well as initial imperfections in global and member levels are considered. Therefore, the section capacity check without the assumption of effective length is adequate for present design and the conventional individual element design is avoided. The uncertainty of the buckling effects and effective length method can be eliminated and so a more economical design can be achieved. Two benchmark steel frames of three-storey and nine-storey in FEMA 440 were analyzed to illustrate the validity of the proposed method.

scholarly journals A Multilevel Approach for the Cultural Heritage Vulnerability and Strengthening: Application to the Melfi Castle

Buildings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 158
Author(s):  
Cristina Cantagallo ◽  
Enrico Spacone ◽  
Daniele Perrucci ◽  
Nicola Liguori ◽  
Clara Verazzo
Keyword(s):  
Structural Integrity ◽  
Seismic Analysis ◽  
Pushover Analysis ◽  
Historical Analysis ◽  
Safety Evaluation ◽  
Soil Survey ◽  
Seismic Safety ◽  
Seismic Safety Evaluation ◽  
Cracking Pattern ◽  
Integrity Analysis

This study outlines a procedure for the seismic safety evaluation of historical buildings for engineers and architects that commonly work on buildings belonging to cultural and architectural heritage. The procedure is characterized by two interrelated phases: (a) building knowledge acquisition and (b) structural behavior analysis and safety assessment. The seismic safety evaluation strongly depends on the first phase, whose data can be obtained according to a multi-disciplinary approach based on five steps: (1) critical-historical analysis; (2) photographic documentation and geometrical survey; (3) structural identification and material survey; (4) foundation and soil survey; and (5) cracking pattern and structural integrity analysis. The proposed method was applied to the evaluation of the seismic safety of the Castle of Melfi (PZ, Italy). Comprehensive and multi-disciplinary knowledge of this monument greatly facilitated an accurate seismic analysis of this monument, which was conducted both at a local and global level using a linear kinematic analysis and non-linear static (pushover) analysis, respectively.

scholarly journals Locating Critical Circular and Unconstrained Failure Surface in Slope Stability Analysis with Tailored Genetic Algorithm

2017 ◽  
Vol 39 (4) ◽  
pp. 87-98
Author(s):  
Tomasz Pasik ◽  
Raymond van der Meij
Keyword(s):  
Genetic Algorithm ◽  
Slope Stability ◽  
Failure Surface ◽  
Computational Effort ◽  
Engineering Practice ◽  
Initial Population ◽  
Detailed Result ◽  
Population Type ◽  
Slip Planes ◽  
The Right

Abstract This article presents an efficient search method for representative circular and unconstrained slip surfaces with the use of the tailored genetic algorithm. Searches for unconstrained slip planes with rigid equilibrium methods are yet uncommon in engineering practice, and little publications regarding truly free slip planes exist. The proposed method presents an effective procedure being the result of the right combination of initial population type, selection, crossover and mutation method. The procedure needs little computational effort to find the optimum, unconstrained slip plane. The methodology described in this paper is implemented using Mathematica. The implementation, along with further explanations, is fully presented so the results can be reproduced. Sample slope stability calculations are performed for four cases, along with a detailed result interpretation. Two cases are compared with analyses described in earlier publications. The remaining two are practical cases of slope stability analyses of dikes in Netherlands. These four cases show the benefits of analyzing slope stability with a rigid equilibrium method combined with a genetic algorithm. The paper concludes by describing possibilities and limitations of using the genetic algorithm in the context of the slope stability problem.

scholarly journals Damage capacity on RC structures using performance based analysis

2021 ◽  
Vol 309 ◽  
pp. 01203
Author(s):  
Kurelly Spandana ◽  
Y.Kamala Raju ◽  
G V V Satyanarayana ◽  
Atulkumar Manchalwar
Keyword(s):  
Static Analysis ◽  
Pushover Analysis ◽  
Building Design ◽  
Rc Structures ◽  
Earthquake Loads ◽  
Software Analysis ◽  
Gravity Load ◽  
Earthquake Resistant ◽  
Pushover Curve ◽  
Rc Building

Performance based analysis is conducted on a structure to know the performance of building under severe earthquake loads with limited and well-distributed damage. To do this analysis a non-linear static analysis called pushover analysis had conducted on the structure. In this paper, an RC building with both 5 storey and 10 storey is designed for both gravity loads and earthquake resistant loads using SAP2000 software. Analysis is done in both X and Y direction to get a damage curve (pushover curve). By studying the damage curve, the results that obtained are earthquake resistant designed building had more strength when compared to gravity load designed building and it is better to consider earthquake in building design , because gravity loads alone cannot give the adequate results.

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