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The aim of this work is to evaluate the influence of the pier–abutment–deck interaction on the seismic response of bridges isolated by single concave sliding pendulum isolators (friction pendulum system [FPS]) through a comparison with the results of the seismic response of isolated bridges without considering the presence of the rigid abutment (i.e., isolated viaducts). Two different multidegree-of-freedom (mdof) models are properly defined to carry out this comparison. In the both mdof models, five vibrational modes are considered to describe the elastic behavior of the reinforced concrete pier, and an additional degree of freedom is adopted to analyze the response of the infinitely rigid deck isolated by the seismic devices. The FPS isolator behavior is described through a widespread velocity-dependent model. By means of a nondimensional formulation of the motion equations with respect to the seismic intensity, a parametric analysis for several structural properties is performed in order to investigate the differences between the two mdof models in relation to the relevant response parameters. The uncertainty in the seismic input is taken into account by means of a set of natural records with different characteristics. Finally, multivariate nonlinear regression relationships are provided to estimate the optimum values of the sliding friction coefficient able to minimize the pier displacements relative to the ground as a function of the structural properties considering or neglecting the presence of the abutment.
Paolo Castaldo; Guglielmo Amendola. Optimal sliding friction coefficients for isolated viaducts and bridges: A comparison study. Structural Control and Health Monitoring 2021, e2838 .
AMA StylePaolo Castaldo, Guglielmo Amendola. Optimal sliding friction coefficients for isolated viaducts and bridges: A comparison study. Structural Control and Health Monitoring. 2021; ():e2838.
Chicago/Turabian StylePaolo Castaldo; Guglielmo Amendola. 2021. "Optimal sliding friction coefficients for isolated viaducts and bridges: A comparison study." Structural Control and Health Monitoring , no. : e2838.
The study analyzes the influence of double concave friction pendulum (DCFP) isolator properties on the seismic performance of isolated multispan continuous deck bridges. The behavior of these systems is analyzed by employing an eight‐degree‐of‐freedom model accounting for the pier flexibility in addition to the rigid presence of both abutment and deck, whereas the DCFP isolator behavior is described combining two single FP devices in series. The uncertainty in the seismic input is taken into account by considering a set of nonfrequent natural records with different characteristics. The variation of the statistics of the response parameters relevant to the seismic performance of the isolated bridges is investigated through the proposal of a nondimensionalization of the motion equations, with respect to the seismic intensity, within an extensive parametric study carried out for different isolator and bridge properties. Moreover, two cases related to different ratios between the sliding friction coefficients of the two surfaces of the DCFP devices are analyzed with the aim also to evaluate the corresponding optimal values able to minimize the seismic demand to the pier. In this way, all the presented nondimensional results are useful for the preliminary design or retrofit of multispan continuous deck bridges, isolated with DCFP devices, located in any site and in relation, especially, to the seismic ultimate limit states.
Paolo Castaldo; Guglielmo Amendola. Optimal DCFP bearing properties and seismic performance assessment in nondimensional form for isolated bridges. Earthquake Engineering & Structural Dynamics 2021, 1 .
AMA StylePaolo Castaldo, Guglielmo Amendola. Optimal DCFP bearing properties and seismic performance assessment in nondimensional form for isolated bridges. Earthquake Engineering & Structural Dynamics. 2021; ():1.
Chicago/Turabian StylePaolo Castaldo; Guglielmo Amendola. 2021. "Optimal DCFP bearing properties and seismic performance assessment in nondimensional form for isolated bridges." Earthquake Engineering & Structural Dynamics , no. : 1.
The present study aims to characterize the epistemic uncertainty within the use of global non‐linear numerical analyses (i.e., NLNAs) for design and assessment purposes of slender reinforced concrete (RC) members. The epistemic uncertainty associated to NLNAs may be represented by approximations and choices performed during the definition of a structural numerical model. In order to quantify epistemic uncertainty associated to a non‐linear numerical simulation, the resistance model uncertainty random variable has to be characterized by means of the comparison between experimental and numerical results. With this aim, a set of experimental tests on slender RC columns known from the literature is considered. Then, the experimental results in terms of maximum axial load are compared to the outcomes achieved from NLNAs. Nine different modeling hypotheses are herein considered to characterize the resistance model uncertainty random variable. The probabilistic analysis of the results has been performed according to Bayesian approach accounting also for both the previous knowledge from the scientific literature and the influence of the experimental uncertainty on the estimation of the statistics of the resistance model uncertainty random variable. Finally, the resistance model uncertainty partial safety factor is evaluated in line with the global resistance format of fib Model Code for Concrete Structures 2010 with reference to new and existing RC structures.
Diego Gino; Paolo Castaldo; Luca Giordano; Giuseppe Mancini. Model uncertainty in non‐linear numerical analyses of slender reinforced concrete members. Structural Concrete 2021, 22, 845 -870.
AMA StyleDiego Gino, Paolo Castaldo, Luca Giordano, Giuseppe Mancini. Model uncertainty in non‐linear numerical analyses of slender reinforced concrete members. Structural Concrete. 2021; 22 (2):845-870.
Chicago/Turabian StyleDiego Gino; Paolo Castaldo; Luca Giordano; Giuseppe Mancini. 2021. "Model uncertainty in non‐linear numerical analyses of slender reinforced concrete members." Structural Concrete 22, no. 2: 845-870.
In many countries around the world a huge number of existing reinforced concrete (RC) structures have been realized without account for seismic detailing, even if they are located in areas subjected to high seismicity. In this context, several passive seismic protection techniques have been developed and applied to retrofit these structures such as, for an example, seismic isolation. The aim of this work is to characterize in probabilistic terms the seismic performance of a framed RC building retrofitted by means of sliding friction pendulum (FPS) devices. Specifically, the response of an existing RC building located in a high seismicity area in Italy is investigated. After the description of the main available information about the structure, a non-linear numerical model has been defined by means of fiber-elements approach. Then, non-linear dynamic analyses considering multiple recorded ground motions with the three accelerometric components have been carried out to assess the seismic response of the building with and without the retrofitting intervention composed of FPS isolators. Finally, the results are processed to achieve a probabilistic assessment of the seismic performance of the retrofitting intervention.
Diego Gino; Costanza Anerdi; Paolo Castaldo; Mario Ferrara; Gabriele Bertagnoli; Luca Giordano. Seismic Upgrading of Existing Reinforced Concrete Buildings Using Friction Pendulum Devices: A Probabilistic Evaluation. Applied Sciences 2020, 10, 8980 .
AMA StyleDiego Gino, Costanza Anerdi, Paolo Castaldo, Mario Ferrara, Gabriele Bertagnoli, Luca Giordano. Seismic Upgrading of Existing Reinforced Concrete Buildings Using Friction Pendulum Devices: A Probabilistic Evaluation. Applied Sciences. 2020; 10 (24):8980.
Chicago/Turabian StyleDiego Gino; Costanza Anerdi; Paolo Castaldo; Mario Ferrara; Gabriele Bertagnoli; Luca Giordano. 2020. "Seismic Upgrading of Existing Reinforced Concrete Buildings Using Friction Pendulum Devices: A Probabilistic Evaluation." Applied Sciences 10, no. 24: 8980.
The use of buckling restrained braces (BRBs) represents one of the best solutions for retrofitting or upgrading the numerous existing reinforced concrete framed buildings in areas with a high seismic hazard. This study investigates the effectiveness of BRBs for the seismic retrofit of reinforced concrete (RC) buildings with masonry infills. For this purpose, an advanced non-linear three-dimensional model of an existing building in L'Aquila is developed in OpenSees, by accounting for the effect of infill walls through an equivalent strut approach, and by using a recently developed hysteretic model for the BRBs. The seismic performance of the building before and after the retrofit with BRBs is evaluated by performing both non-linear static analyses and incremental dynamic analyses under a set of real ground motion records along the weak direction of the frame. Seismic demand hazard curves are built for different response parameters before and after the retrofit, by accounting for and by disregarding the contribution of the infill walls. The study results shed light on the effect of the BRBs and of the infill walls on the seismic performance of the various components of the system, and on the effectiveness of the retrofit with BRBs for a real case study.
P. Castaldo; E. Tubaldi; F. Selvi; L. Gioiella. Seismic performance of an existing RC structure retrofitted with buckling restrained braces. Journal of Building Engineering 2020, 33, 101688 .
AMA StyleP. Castaldo, E. Tubaldi, F. Selvi, L. Gioiella. Seismic performance of an existing RC structure retrofitted with buckling restrained braces. Journal of Building Engineering. 2020; 33 ():101688.
Chicago/Turabian StyleP. Castaldo; E. Tubaldi; F. Selvi; L. Gioiella. 2020. "Seismic performance of an existing RC structure retrofitted with buckling restrained braces." Journal of Building Engineering 33, no. : 101688.
This study employs the seismic reliability-based design approach for inelastic structures isolated by friction pendulum isolators, considering two different highly seismic Italian sites to provide useful design recommendations. Incremental dynamic analyses are carried out to estimate the seismic fragility of the superstructure and of devices, assuming different structural properties and limit state thresholds. Finally, considering seismic hazard curves of the investigated sites, seismic reliability-based design curves are proposed to derive the dimensions in plan of devices and the ductility demand of the superstructure as a function of both the structural properties and the reliability level expected. The proposed results confirm the possibility of using seismic reliability-based design as a sustainable and applicable approach and represent a large data set to adopt this design methodology in any site with a similar seismic hazard.
Paolo Castaldo; Tatiana Ferrentino. Seismic Reliability-Based Design Approach for Base-Isolated Systems in Different Sites. Sustainability 2020, 12, 2400 .
AMA StylePaolo Castaldo, Tatiana Ferrentino. Seismic Reliability-Based Design Approach for Base-Isolated Systems in Different Sites. Sustainability. 2020; 12 (6):2400.
Chicago/Turabian StylePaolo Castaldo; Tatiana Ferrentino. 2020. "Seismic Reliability-Based Design Approach for Base-Isolated Systems in Different Sites." Sustainability 12, no. 6: 2400.
This study assesses the partial safety factor corresponding to the resistance model uncertainties in the use of non-linear finite element analyses (NLFEAs) for reinforced concrete systems subjected to cyclic loads. Specifically, various walls experimentally tested are considered for this investigation and are simulated through two-dimensional (i.e., plane stress) finite element (NLFE) models. The comparison between the global resistances from the plane stress NLFE structural models and the experimental tests is carried out considering the possible modelling hypotheses available in relation to the mechanical response of reinforced concrete structural systems subjected to cyclic loads. After that, a probabilistic processing of the abovementioned epistemic uncertainties is carried out in line with a Bayesian updating. In detail, each prior distribution of the resistance model uncertainty related to a specific combination of the modelling hypotheses is computed and successively updated with the data achieved from the other models to estimate the posterior distribution. Hence, the coefficient of variation and the mean value of the resistance model uncertainties are evaluated and the corresponding partial safety factor is assessed in line with the NLFEA safety formats of reinforced concrete systems for seismic analyses.
Paolo Castaldo; Diego Gino; Gabriele Bertagnoli; Giuseppe Mancini. Resistance model uncertainty in non-linear finite element analyses of cyclically loaded reinforced concrete systems. Engineering Structures 2020, 211, 110496 .
AMA StylePaolo Castaldo, Diego Gino, Gabriele Bertagnoli, Giuseppe Mancini. Resistance model uncertainty in non-linear finite element analyses of cyclically loaded reinforced concrete systems. Engineering Structures. 2020; 211 ():110496.
Chicago/Turabian StylePaolo Castaldo; Diego Gino; Gabriele Bertagnoli; Giuseppe Mancini. 2020. "Resistance model uncertainty in non-linear finite element analyses of cyclically loaded reinforced concrete systems." Engineering Structures 211, no. : 110496.
The assessment of existing reinforced concrete structures is one of the major aspects for engineers and practitioners. In particular, existing infrastructures, as bridges and viaducts, are extensively exposed to environmental actions, materials aging, degradation, and variation of magnitude of traffic loads during their service life. Hence, the assessment of existing structural systems assuming the same criteria conceived for the design (i.e., partial factor method—EN 1990) can be too conservative and, sometimes, may lead to unnecessary and expensive structural interventions. In this context, fib Bulletin 80 defines the partial factor methods suitable for the assessment of existing reinforced concrete structures accounting for their residual service life, information from in situ and laboratory tests, measurements of variable actions and reduced target reliability levels according to both economical and human safety criteria. The methodologies proposed in fib Bulletin 80 have been applied to assess the safety of an existing prestressed reinforced concrete bridge built in 90s and located in Italy. The results are compared to the outcomes from the assessment performed according to EN1990 and, finally, limits and advantages of the methodologies proposed by fib Bulletin 80 are discussed.
Diego Gino; Paolo Castaldo; Gabriele Bertagnoli; Luca Giordano; Giuseppe Mancini. Partial factor methods for existing structures according to fib Bulletin 80: Assessment of an existing prestressed concrete bridge. Structural Concrete 2019, 21, 15 -31.
AMA StyleDiego Gino, Paolo Castaldo, Gabriele Bertagnoli, Luca Giordano, Giuseppe Mancini. Partial factor methods for existing structures according to fib Bulletin 80: Assessment of an existing prestressed concrete bridge. Structural Concrete. 2019; 21 (1):15-31.
Chicago/Turabian StyleDiego Gino; Paolo Castaldo; Gabriele Bertagnoli; Luca Giordano; Giuseppe Mancini. 2019. "Partial factor methods for existing structures according to fib Bulletin 80: Assessment of an existing prestressed concrete bridge." Structural Concrete 21, no. 1: 15-31.
This work estimates the partial safety factor corresponding to the resistance model uncertainties in non-linear finite element method analyses (NLFEAs) of reinforced concrete structures considering various structural typologies with different behaviours and failure modes (i.e., walls, deep beams, panels). The comparison between the two-dimensional NLFE structural model results and the experimental outcomes is carried out considering the possible solution strategies available to describe the mechanical behaviour of reinforced concrete members in different software codes. Several NLFE structural models are defined for each experimental test in order to investigate the resistance model uncertainty. Then, a consistent treatment of the resistance model uncertainties is proposed following a Bayesian approach identifying the mean value and the coefficient of variation of the resistance model uncertainties. Finally, in agreement with the safety formats for NLFEAs of reinforced concrete structures, the partial safety factor is calibrated.
P. Castaldo; D. Gino; D. La Mazza; G. Bertagnoli; V. I. Carbone; G. Mancini. Assessment of the Partial Safety Factor Related to Resistance Model Uncertainties in 2D NLFEAs of R.C. Systems. Proceedings of EECE 2020 2019, 3 -15.
AMA StyleP. Castaldo, D. Gino, D. La Mazza, G. Bertagnoli, V. I. Carbone, G. Mancini. Assessment of the Partial Safety Factor Related to Resistance Model Uncertainties in 2D NLFEAs of R.C. Systems. Proceedings of EECE 2020. 2019; ():3-15.
Chicago/Turabian StyleP. Castaldo; D. Gino; D. La Mazza; G. Bertagnoli; V. I. Carbone; G. Mancini. 2019. "Assessment of the Partial Safety Factor Related to Resistance Model Uncertainties in 2D NLFEAs of R.C. Systems." Proceedings of EECE 2020 , no. : 3-15.
This study evaluates the seismic robustness of 3D r.c. structures isolated with single-concave friction pendulum system (FPS) devices by computing the seismic reliability of different models related to different malfunction cases of the seismic isolators. Considering the elastic response pseudo-acceleration as the relevant random variable, the input data have been defined by means of the Latin Hypercube Sampling technique in order to develop 3D inelastic time-history analyses. In this way, bivariate structural performance curves at each level of the r.c. structural systems as well as seismic reliability-based design abacuses for the FP devices have been computed and compared in order to evaluate the robustness of the r.c. system considering different failure cases of the FP bearings. Moreover, the seismic robustness is examined by considering both a configuration equipped with beams connecting the substructure columns and a configuration without these connecting beams in order to demonstrate their effectiveness and provide useful design recommendations for base-isolated structural systems equipped with FPS.
P. Castaldo; G. Mancini; B. Palazzo. Robustness of 3D Base-Isolated R.C. Systems with FPS. Proceedings of EECE 2020 2019, 16 -27.
AMA StyleP. Castaldo, G. Mancini, B. Palazzo. Robustness of 3D Base-Isolated R.C. Systems with FPS. Proceedings of EECE 2020. 2019; ():16-27.
Chicago/Turabian StyleP. Castaldo; G. Mancini; B. Palazzo. 2019. "Robustness of 3D Base-Isolated R.C. Systems with FPS." Proceedings of EECE 2020 , no. : 16-27.
The study describes some proposals regarding the safety formats (i.e., global resistance methods (GRMs) and probabilistic method (PM)) for non-linear finite element analysis within the approach of the global resistance format to estimate the design strength of reinforced concrete structures. Specifically, non-linear finite element models are properly defined to reproduce various experimental tests. Successively, several non-linear finite element analyses are carried out in compliance with the different safety formats for each reinforced concrete structure experimentally tested in order to compare and critically discuss the results in terms of resistance and failure mode. In fact, the different safety formats are investigated to demonstrate if they are able to estimate the corresponding design global resistance capacities and to capture any possible modification in the failure mode for each structure considering the aleatory uncertainties. Then, a methodology based on a specific preliminary evaluation, composed of two non-linear finite element analyses, is proposed to verify the applicability of the simplified GRMs depending on the possible modifications that can occur in the failure mode in comparison with the PM taking into account the aleatory uncertainty on the materials properties. Moreover, in the cases when any GRM cannot be used, the PM is suggested as the unique safety format able to estimate an appropriate value of the global design structural resistance due to the possible modifications in the structural response by the effect of combination of the actual materials strengths. Finally, in order to apply GRMs for their reduced computational effort also in the abovementioned cases, an additional failure mode-based safety factor is proposed for the assessment of the design global resistance.
Paolo Castaldo; Diego Gino; Giuseppe Mancini. Safety formats for non-linear finite element analysis of reinforced concrete structures: discussion, comparison and proposals. Engineering Structures 2019, 193, 136 -153.
AMA StylePaolo Castaldo, Diego Gino, Giuseppe Mancini. Safety formats for non-linear finite element analysis of reinforced concrete structures: discussion, comparison and proposals. Engineering Structures. 2019; 193 ():136-153.
Chicago/Turabian StylePaolo Castaldo; Diego Gino; Giuseppe Mancini. 2019. "Safety formats for non-linear finite element analysis of reinforced concrete structures: discussion, comparison and proposals." Engineering Structures 193, no. : 136-153.
This study deals with the seismic fragility of elastic structural systems equipped with single concave sliding (friction pendulum system (FPS)) isolators considering different soil conditions. The behavior of these systems is analyzed by employing a two-degree-of-freedom model, whereas the FPS response is described by means of a velocity-dependent model. The uncertainty in the seismic inputs is taken into account by considering artificial seismic excitations modelled as timemodulated filtered Gaussian white noise random processes of different intensity within the power spectral density method. In particular, the filter parameters, which control the frequency content of the random excitations, are calibrated to describe stiff, medium and soft soil conditions. The sliding friction coefficient at large velocity is also considered as a random variable modelled through a uniform probability density function. Incremental dynamic analyses are developed in order to evaluate the probabilities of exceeding different limit states related to both the reinforced concrete (RC) superstructure and isolation level, defining the seismic fragility curves within an extensive parametric study carried out for different structural system properties and soil conditions. The abovementioned seismic fragility curves are useful to evaluate the seismic reliability of base-isolated elastic systems equipped with FPS and located in any site for any soil condition.
P. Castaldo; G. Amendola; M. Ripani. Seismic fragility of structures isolated by single concave sliding devices for different soil conditions. Earthquake Engineering and Engineering Vibration 2018, 17, 869 -891.
AMA StyleP. Castaldo, G. Amendola, M. Ripani. Seismic fragility of structures isolated by single concave sliding devices for different soil conditions. Earthquake Engineering and Engineering Vibration. 2018; 17 (4):869-891.
Chicago/Turabian StyleP. Castaldo; G. Amendola; M. Ripani. 2018. "Seismic fragility of structures isolated by single concave sliding devices for different soil conditions." Earthquake Engineering and Engineering Vibration 17, no. 4: 869-891.
This work evaluates the partial safety factor related to the resistance model uncertainties in non-linear finite element analyses (NLFEAs) for reinforced concrete structures. Various experimental tests concerning different typologies of structures with different behaviours and failure modes, i.e., walls, deep beams, panels, are simulated by means of appropriate two-dimensional finite elements (FE) structural models (i.e., plane stress configuration). Several FE structural models are defined for each experimental test to investigate the model uncertainty influence on the 2D NLFEAs of reinforced concrete structures in terms of global resistance, considering different modelling hypotheses to describe the mechanical behaviour of reinforced concrete members (i.e., epistemic uncertainties). Subsequently, the numerical results are compared to the experimental outcomes. Then, a consistent treatment of the resistance model uncertainties is proposed following a Bayesian approach. Specifically, the prior distributions of the resistance model uncertainties for the different modelling hypotheses are evaluated and then each one is updated on the basis of the data obtained from the other models to evaluate the posterior distributions. After that, the mean value and the coefficient of variation characterizing the resistance model uncertainties are identified. Finally, in agreement with the safety formats for NLFEAs of reinforced concrete structures, the partial safety factor related to the resistance model uncertainties is evaluated.
Paolo Castaldo; Diego Gino; Gabriele Bertagnoli; Giuseppe Mancini. Partial safety factor for resistance model uncertainties in 2D non-linear finite element analysis of reinforced concrete structures. Engineering Structures 2018, 176, 746 -762.
AMA StylePaolo Castaldo, Diego Gino, Gabriele Bertagnoli, Giuseppe Mancini. Partial safety factor for resistance model uncertainties in 2D non-linear finite element analysis of reinforced concrete structures. Engineering Structures. 2018; 176 ():746-762.
Chicago/Turabian StylePaolo Castaldo; Diego Gino; Gabriele Bertagnoli; Giuseppe Mancini. 2018. "Partial safety factor for resistance model uncertainties in 2D non-linear finite element analysis of reinforced concrete structures." Engineering Structures 176, no. : 746-762.
This work aims at the development of an advanced method for the seismic design of Moment Resisting Frames (MRFs) based on a target value of the failure probability in the attainment of a collapse mechanism of global type for stochastic frames (considering the aleatoric uncertainty of the material properties). Therefore, the method herein presented constitutes the probabilistic version of the Theory of Plastic Mechanism Control (TPMC) already developed for frames with deterministic material properties. With reference to MRFs whose members have random values of the yield strength, when structural collapse is of concern, the failure domain is related to all the possible collapse mechanisms. Within the probabilistic TPMC, the term “failure” does not mean the attainment of a structural collapse, but the development of a collapse mechanism different from the global one. The design requirements normally needed to prevent undesired collapse mechanisms are probabilistic events within the framework of the kinematic theorem of plastic collapse. The limit state function corresponding to each event is represented by a hyperplane in the space of random variables, so that the failure domain is a surface resulting from the intersection of the hyperplanes corresponding to the limit states representing the single failure events. Since plastic hinges in frame’s members are common to many different mechanisms, the single limit state events are correlated. Therefore, by applying the theory of binary systems and considering that the limit states are events located in series, the probability of failure can be computed by means of Ditlevsen bounds. This approach has been validated by means of Monte Carlo simulations. In order to achieve a predefined level of reliability in the attainment of the design goal, the reliability analysis is repeated for increasing values of the overstrength factor of the dissipative zones to be used in TPMC, aiming to its calibration. Finally, on the basis of the results of a parametric analysis, a simple relationship to compute the value of the overstrength factor needed to include the influence of random material variability in the application of TPMC is proposed.
Vincenzo Piluso; Alessandro Pisapia; Paolo Castaldo; Elide Nastri. Probabilistic Theory of Plastic Mechanism Control for Steel Moment Resisting Frames. Structural Safety 2018, 76, 95 -107.
AMA StyleVincenzo Piluso, Alessandro Pisapia, Paolo Castaldo, Elide Nastri. Probabilistic Theory of Plastic Mechanism Control for Steel Moment Resisting Frames. Structural Safety. 2018; 76 ():95-107.
Chicago/Turabian StyleVincenzo Piluso; Alessandro Pisapia; Paolo Castaldo; Elide Nastri. 2018. "Probabilistic Theory of Plastic Mechanism Control for Steel Moment Resisting Frames." Structural Safety 76, no. : 95-107.
This study aims at proposing seismic reliability‐based relationships between the behavior factors and the displacement demand for nonlinear hardening and softening structures isolated by friction pendulum system devices considering several structural properties. An equivalent 2dof model having both a hardening and softening postyield slope is used to describe the superstructure behavior, whereas a velocity‐dependent model is adopted for the friction pendulum system response. The yielding characteristics of the superstructures, related to life safety limit state, are designed according to the seismic hazard of L'Aquila site (Italy) for increasing behavior factors, as provided from NTC08. Considering natural seismic records and several elastic and inelastic building properties, different postyield hardening and softening stiffness values, different seismic intensity levels, and modeling the friction coefficient as a random variable, incremental dynamic analyses are performed to evaluate the seismic fragility of these structural systems. By means of the convolution integral between the fragility curves and the seismic hazard curves corresponding to L'Aquila site (Italy), the reliability curves of the equivalent hardening and softening base‐isolated structural systems, with a lifetime of 50 years, are defined. Specifically, seismic reliability‐based linear and multilinear regression expressions between the displacement ductility demand and the behavior factors for the superstructure as well as seismic reliability‐based design abacuses for the friction pendulum devices are proposed.
Paolo Castaldo; Bruno Palazzo; Gaetano Alfano; Mario Francesco Palumbo. Seismic reliability-based ductility demand for hardening and softening structures isolated by friction pendulum bearings. Structural Control and Health Monitoring 2018, 25, e2256 .
AMA StylePaolo Castaldo, Bruno Palazzo, Gaetano Alfano, Mario Francesco Palumbo. Seismic reliability-based ductility demand for hardening and softening structures isolated by friction pendulum bearings. Structural Control and Health Monitoring. 2018; 25 (11):e2256.
Chicago/Turabian StylePaolo Castaldo; Bruno Palazzo; Gaetano Alfano; Mario Francesco Palumbo. 2018. "Seismic reliability-based ductility demand for hardening and softening structures isolated by friction pendulum bearings." Structural Control and Health Monitoring 25, no. 11: e2256.
The aim of this work is to evaluate the optimal properties of friction pendulum system (FPS) bearings for the seismic protection of bridge piers under earthquake excitations having different frequency characteristics representative of different soil conditions in order to reduce the seismic vulnerability of infrastructures increasing their safety level. A two-degree-of-freedom model is adopted to describe, respectively, the response of the infinitely rigid deck isolated by the FPS devices and the elastic behaviour of the pier. The FPS isolator behaviour is modeled through a widespread velocity-dependent rule. By means of a non-dimensional formulation of the motion equations, proposed in this study, a wide parametric analysis considering several structural parameters is performed to investigate their influence on the response parameters relevant to the performance assessment. Seismic excitations, modeled as time-modulated filtered Gaussian white noise random processes having different intensities and frequency contents, are considered. Specifically, the filter parameters, which control the frequency contents, are properly calibrated to reproduce stiff, medium and soft soil conditions, respectively. Finally, multi-variate non-linear regression relationships are derived to estimate the optimum values of the sliding friction coefficient able to minimize a percentile of the pier displacements relative to the ground as a function of the structural properties, of the seismic input intensity and of the soil condition.
P. Castaldo; M. Ripani; R. Lo Priore. Influence of soil conditions on the optimal sliding friction coefficient for isolated bridges. Soil Dynamics and Earthquake Engineering 2018, 111, 131 -148.
AMA StyleP. Castaldo, M. Ripani, R. Lo Priore. Influence of soil conditions on the optimal sliding friction coefficient for isolated bridges. Soil Dynamics and Earthquake Engineering. 2018; 111 ():131-148.
Chicago/Turabian StyleP. Castaldo; M. Ripani; R. Lo Priore. 2018. "Influence of soil conditions on the optimal sliding friction coefficient for isolated bridges." Soil Dynamics and Earthquake Engineering 111, no. : 131-148.
The study proposes a framework based on the Monte Carlo method for the probabilistic calibration of empirical and semi‐empirical resisting models. The resisting models adopted in engineering practice may be based both on physical laws, such as equilibrium of forces, and on semi‐empirical or empirical formulations. Precisely, empirical or semi‐empirical resisting models are calibrated in order to fit experimental data and the direct application of partial safety factors to material properties does not allow a proper estimation of the structural reliability. For this reason, a probabilistic definition of design expressions from empirical or semi‐empirical resisting models should be preferred to define a final formulation in agreement with a specific level of reliability. After a detailed description of the framework, its application to the probabilistic calibration of the semi‐empirical model proposed by fib Model Code 2010 for the estimation of tensile strength of laps and anchorages in reinforced concrete structures is proposed.
Paolo Castaldo; Diego Gino; Vincenzo Ilario Carbone; Giuseppe Mancini. Framework for definition of design formulations from empirical and semi-empirical resistance models. Structural Concrete 2018, 19, 980 -987.
AMA StylePaolo Castaldo, Diego Gino, Vincenzo Ilario Carbone, Giuseppe Mancini. Framework for definition of design formulations from empirical and semi-empirical resistance models. Structural Concrete. 2018; 19 (4):980-987.
Chicago/Turabian StylePaolo Castaldo; Diego Gino; Vincenzo Ilario Carbone; Giuseppe Mancini. 2018. "Framework for definition of design formulations from empirical and semi-empirical resistance models." Structural Concrete 19, no. 4: 980-987.
Reinforced concrete structures in service may be affected by aging, which may include changes in strength and stiffness assumed in structural design, in particular when the concrete is exposed to an aggressive environment. In this context, this paper provides a computational probabilistic approach to predict the time-evolution of the mechanical and geometrical properties of a statically determinate r.c. structural system (i.e. bridge pier) subjected to corrosion-induced deterioration, due to diffusive attack of chlorides, in order to evaluate its service life. Adopting appropriate degradation models of the material properties, concrete and reinforcing steel, as well as assuming appropriate probability density functions related to mechanical and deterioration parameters, the proposed model is based on Monte Carlo simulations in order to evaluate time variant axial force-bending moment resistance domains, with the aim to estimate the time-variant reliability index. Finally, an application to estimate the expected lifetime of a r.c. bridge pier is described.
P. Castaldo; B. Palazzo; A. Mariniello. Lifetime Axial-Bending Capacity of a R.C. Bridge Pier Cross-Section Subjected to Corrosion. Proceedings of EECE 2020 2018, 371 -384.
AMA StyleP. Castaldo, B. Palazzo, A. Mariniello. Lifetime Axial-Bending Capacity of a R.C. Bridge Pier Cross-Section Subjected to Corrosion. Proceedings of EECE 2020. 2018; ():371-384.
Chicago/Turabian StyleP. Castaldo; B. Palazzo; A. Mariniello. 2018. "Lifetime Axial-Bending Capacity of a R.C. Bridge Pier Cross-Section Subjected to Corrosion." Proceedings of EECE 2020 , no. : 371-384.
This study aims to evaluate the seismic performances of bridges isolated by the friction pendulum system (FPS) bearings considering the seismic hazard of Sant’Angelo dei Lombardi site (Italy), to provide useful and preliminary recommendations in terms of health assessment for design or retrofit of new or existing bridges, respectively. Single- and two-degree-of-freedom models are considered to describe the isolated bridge behavior taking into account an infinitely rigid deck and the isolated bridge behavior having an infinitely rigid deck with the elastic pier, respectively. In both models, a velocity-dependent rule for the FPS isolators is assumed. Seismic excitations are properly modeled as non-stationary stochastic processes having different intensities corresponding to different limit states and with frequency contents related to the medium soil condition, representative of the soil type in Sant’Angelo dei Lombardi site (Italy). The statistics of deck and pier responses of the isolated bridge are evaluated for different system parameters such as mass ratio, isolation period, pier period and friction coefficient of the FPS considering both Life Safety and Collapse Prevention limit states according to Italian seismic codes. The results, deriving mainly from the two-degree-of-freedom (2dof) model analyses, show that particular values of the friction coefficient allow to minimize the response of the pier depending on the different system properties and the different limit states. In particular, the optimum friction coefficient of the FPS ranges from 0.01 to 0.04 and from 0.01 to 0.05 for Life Safety and for Collapse Prevention limit state, respectively, depending on the structural properties.
P. Castaldo; R. Lo Priore. Seismic performance assessment of isolated bridges for different limit states. Journal of Civil Structural Health Monitoring 2017, 8, 17 -32.
AMA StyleP. Castaldo, R. Lo Priore. Seismic performance assessment of isolated bridges for different limit states. Journal of Civil Structural Health Monitoring. 2017; 8 (1):17-32.
Chicago/Turabian StyleP. Castaldo; R. Lo Priore. 2017. "Seismic performance assessment of isolated bridges for different limit states." Journal of Civil Structural Health Monitoring 8, no. 1: 17-32.
This work aims at the development of an advanced method for the seismic design of Moment Resisting Frames (MRFs) based on the evaluation of the probability of failure in the attainment of a collapse mechanism of global type in case of stochastic frames. Therefore, the method presented constitutes the probabilistic version of the Theory of Plastic Mechanism Control (TPMC) already successfully developed for frames with deterministic material properties. With reference to MRFs whose members have random values of the yield strength, the failure domain derives from all the possible collapse mechanisms. Under the point of view of structural reliability analysis, the term “failure” means the attainment of a collapse mechanism different from the global one. The design requirements normally needed to prevent undesired collapse mechanisms are probabilistic events within the framework of the kinematic theorem of plastic collapse. At each event corresponds a limit state function representing a hyperplane in the space of the random variables, so that the failure domain is a manifold surface resulting from the intersection of the hyperplanes corresponding to the limit states of the single events. Because of plastic hinges in frame's members are common to many different mechanisms, the single limit state events are correlated. Therefore, by applying the theory of binary systems and taking into account that, from the structural reliability point of view, the limit states are events located in series, the probability of failure is computed by means of Ditlevsen bounds.
Paolo Castaldo; Elide Nastri; Vincenzo Piluso; Alessandro Pisapia. 11.10: Probabilistic theory of plastic mechanism control. ce/papers 2017, 1, 2906 -2915.
AMA StylePaolo Castaldo, Elide Nastri, Vincenzo Piluso, Alessandro Pisapia. 11.10: Probabilistic theory of plastic mechanism control. ce/papers. 2017; 1 (2-3):2906-2915.
Chicago/Turabian StylePaolo Castaldo; Elide Nastri; Vincenzo Piluso; Alessandro Pisapia. 2017. "11.10: Probabilistic theory of plastic mechanism control." ce/papers 1, no. 2-3: 2906-2915.