Pere Roca - Academia.edu (original) (raw)
Papers by Pere Roca
Simulation of in-plane shear test on masonry walls using micro modeling tecniques
Material Characterization and Micro-Modeling of a Historic Brick Masonry Pillar
International Journal of Architectural Heritage, Mar 4, 2016
ABSTRACT A masonry pillar composed of solid clay bricks, cement mortar and infill is extracted fr... more ABSTRACT A masonry pillar composed of solid clay bricks, cement mortar and infill is extracted from a historical structure and tested in concentric compression. It is subjected to cyclic and monotonic loads up to compressive failure. In parallel, samples are extracted from the pillar and are subjected to destructive tests. Non-destructive tests are performed on the pillar, as well. The properties of the constituent materials are critically examined and their role in the maximum load reached and the failure mode obtained are discussed. Finally, a finite element micro-model of the pillar is used for the simulation of the pillar test. The influence of the existing damage on the pillar is investigated using the model, resulting in a fair approximation of the global Young’s modulus, maximum load and the failure mode. Highlights ● A brick masonry pillar extracted from a historical building is tested in compression. ● Material samples extracted from the pillar are characterized by mechanical tests. ● A finite element micro-model of the pillar is used for the simulation of the compressive test. ● The effect of damage on the compressive strength of the pillar is numerically investigated.
A series of experimental tests involving in-plane shear loading of masonry walls is numerically s... more A series of experimental tests involving in-plane shear loading of masonry walls is numerically simulated using finite element detailed micro models. The experimental tests were performed on masonry walls composed of solid clay bricks and cement/lime mortar. The mechanical properties of the two constituent materials and the brick-mortar interface had been previously characterized. The walls were subjected to shear under varying levels of uni-form vertical pre-stress. The finite element models are created by modeling the bricks, mortar and the brick-mortar interface separately. In this manner the failure due to shear, tension or compression can be modelled in each component individually. Nonlinear constitutive laws to model cracking under tension and yielding under compression are used for the continuum elements modelling the units and the mortar. For the tension and shear failure of the interfaces a friction-tension cut off model is employed. Good agreement is found between the expe...
A set of experimental tests to determine the compressive strength of masonry stack prisms has bee... more A set of experimental tests to determine the compressive strength of masonry stack prisms has been numerically simulated using a combined plasticity-smeared crack constitutive law employed in three-dimensional analysis. Supported by an experimental campaign for the mechanical characterization of lime mortar masonry, a series of finite element analyses was performed in an attempt to assess the capacity of the model to reproduce the results obtained in terms of capacity, failure mode and global stiffness. The constitutive law used for the non-linear analysis of the masonry is a combination of a smeared cracking model in tension and a pressure dependent plasticity model in compression, which is capable of accounting for all failure mechanisms that may arise in concentric compression of masonry, both in the units and in the mortar. The purpose of this investigation is to establish whether a numerical approach based on the micro-modeling method is suitable for the simulation of the salient features encountered in masonry under compression as well as highlighting the main material properties necessary to be determined in order to properly model such experiments. The results are expanded upon through a parametric investigation.
For preserving existing structures to the extent possible, vibration-based damage detection techn... more For preserving existing structures to the extent possible, vibration-based damage detection techniques are gaining more attention. In specific, tracking the changes in a structure's natural frequencies employing the Principal Component Analysis (PCA) seems to be a promising technique. This paper presents an ongoing research for developing an approach for damage detection based on identifying the natural frequencies of the structure (via dynamic identification or monitoring) followed by applying PCA on the temporal variation of the identified natural frequencies. The processing of the dynamic monitoring data was carried out using a proposed semiautomatic algorithm able to identify and track the natural frequencies of the monitored structures and their changes over time. The algorithm was applied on one historical structure and two modern ones. PCA will to be carried out. The so far developed approach as a whole was applied on a steel structure model tested in lab. It was subjected to dynamic identification tests with and without damage. It was found that PCA applied to frequency variation seems to be a possible tool to know damages in structures. Nevertheless, the simplified point of view correlating directly the number of PCs with the damage importance seems to be not accurate. First results seem to indicate that the variance percentage explained by each of the principal components could be correlated with the kind of damages and the shake used to excite the structure.
The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathe... more The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathedral. This cathedral is an extraordinary historical construction dating back to the middle ages. The experimental modal parameters of the cathedral were identified using Ambient Vibration Testing (AVT). The cathedral numerical model was updated using the identified modal parameters. This updated model was then used to study the seismic response of the cathedral using non-linear static (pushover) analysis. A sensitively analysis was carried out to reveal the dependency of the seismic capacity on the input materials properties. To assess the seismic performance and the safety of the cathedral, the N2 method was employed. It was found that the cathedral is safe when subjected to the earthquakes expected in Mallorca Island.
The paper presents the current state of an on-going research aimed at characterizing the seismic ... more The paper presents the current state of an on-going research aimed at characterizing the seismic response of Mallorca cathedral. Mallorca cathedral is an audacious Gothic structure built in the island of Mallorca during 14 th -16 th centuries, characterized for its large dimensions and slender structural members. So far, experimental and numerical modal analysis, in addition to tentative model updating and seismic analysis, have been performed. The dynamic identification tests have been carried out by ambient vibration testing, while the frequency domain decomposition (FDD) technique has been used to obtain the modal parameters. A 3D Finite Element (FE) model has been used to determine the vibration modes. The model has been updated by modifying some structural parameters to improve the matching between experimental and numerical modal parameters. Once updated, the model has been utilized to study the seismic response of the cathedral using non-linear static pushover analysis. Conclusions on the possible collapse mechanisms and the seismic performance of the structure are presented.
This paper represents a continuation of a review on the seismic safety assessment of historical s... more This paper represents a continuation of a review on the seismic safety assessment of historical structures using some selected integrated investigation activities. In the first part of this review the dynamic investigation was presented. Here a focus is made on the updating of the numerical models used in the assessment phase and the used techniques in the seismic evaluation.
Assessment of seismic safety of historical structures is a challenging task because the informati... more Assessment of seismic safety of historical structures is a challenging task because the information available about the assessed structure is usually limited. Therefore, it is often necessary to exploit a number of integrated investigation activities to increase the level of knowledge about the historical structure under consideration. Thus, in the case of any need for providing the structure with strengthening intervention, this intervention will be a minimal and any unnecessary strengthening operations will be avoided. This paper presents a literature review carried out to cover the current state-of-the-art of a number of investigation activities carried out integrally for the seismic safety assessment of historical structures. It is presented in two parts. In this first part, the covered topic is the dynamic investigation of historical structures which includes the dynamic identification tests, the dynamic monitoring, and the modal parameters identification methods with the classical and the advanced techniques like the peak picking and the stochastic subspace identification.
The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathe... more The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathedral. This cathedral is an extraordinary historical construction dating back to the middle ages. The experimental modal parameters of the cathedral were identified using Ambient Vibration Testing (AVT). The cathedral numerical model was updated using the identified modal parameters. This updated model was then used to study the seismic response of the cathedral using non-linear static (pushover) analysis. A sensitively analysis was carried out to reveal the dependency of the seismic capacity on the input materials properties. To assess the seismic performance and the safety of the cathedral, the N2 method was employed. It was found that the cathedral is safe when subjected to the earthquakes expected in Mallorca Island.
Contribution of inspection techniques to the assessment of historical structures
Article
The presented research aimed at studying the dynamic behavior of Mallorca cathedral (Mallorca Isl... more The presented research aimed at studying the dynamic behavior of Mallorca cathedral (Mallorca Island, Spain) under ambient sources of vibration and seismic events. The cathedral is one of the greatest built masonry structures worldwide. It is characterized for its audacious dimensions and slender structural members. Because of it, the study of its dynamic behavior is a clear concern. The cathedral dynamic properties were firstly identified using ambient vibration testing. Afterwards, a dynamic monitoring system was implemented to continuously measure, record, and wirelessly transfer the acceleration records without having to set up an activating threshold. This monitoring type was implemented because of the low seismic intensity of Mallorca Island with a basic ground acceleration of only 0.04 g according to the Spanish seismic standard. The continuous monitoring allowed for capturing some seismic events and some drops in the natural frequencies were noticed because of a breathing crack effect. Using both ambient vibration testing and continuous monitoring system, global modes could be more accurately identified than more local ones. The identification of the global modes was more attainable than in the case of more local ones. The temperature was a more influential environmental parameter than humidity and wind for all of the identified modes except for one more directly depended on wind.
The paper presents the results of experimental research on the structural behavior of dry joint m... more The paper presents the results of experimental research on the structural behavior of dry joint masonry. The most relevant experimental results concern the strength response of stone dry joint masonry walls subjected to in-plane combined compressive and shear loading. Significant features of the structural behavior shown by the walls are discussed and conclusions on their ultimate capacity and observed failure mechanisms are addressed. Complementarily, the application of an existing numerical model, stemming from plasticity and based on a micromodeling strategy, is also presented and discussed with regard to its capacity to simulate the obtained experimental results. The model was calibrated with data collected from complementary tests carried out on specimens and prisms made of the same type of stone. Finally, the usage of a simplified method of analysis based on a continuum of diagonal struts is also addressed.
Non Linear Response of Masonry Wall Structures Subjected to Cyclic and Dynamic Loading
Engineering Structures, Jan 1, 2011
The assessment of the dynamic or seismic performance of complex structures often requires the int... more The assessment of the dynamic or seismic performance of complex structures often requires the integration in the time domain of the structural equation of motion in the frame of a nonlinear analysis. Although sophisticated methods have been developed for the nonlinear analysis of masonry wall structures, including the macro- and micro-modeling approaches, these require large computational effort still limiting the extent and complexity of the structures analyzed. This paper presents an alternative method based on the Generalized Matrix Formulation for masonry skeletal structures and load bearing wall systems, which has been proved as an efficient formulation for the analysis of the strength capacity of these kinds of structures (Roca et al. (2005) [17]). The basic formulation has been complemented with a uniaxial cyclic constitutive model for masonry and a time integration scheme. The ability of the resulting approach to predict the nonlinear dynamic response of masonry structures is shown through its application to the time domain analysis of an experimental scale masonry building with available experimental results on its dynamic response.
Engineering structures, Jan 1, 2008
A constitutive model for concrete subjected to cyclic loadings in both compression and tension is... more A constitutive model for concrete subjected to cyclic loadings in both compression and tension is presented. The proposed model is intended to provide improvements on modelling the cyclic behaviour of concrete structures in the context of computational programs based on a smeared crack approach. Particular emphasis has been paid to the description of the strength and stiffness degradation produced by the load cycling in both tension and compression, the shape of unloading and reloading curves and the transition between opening and closing of cracks. Two independent damage parameters in compression and in tension have been introduced to model the concrete degradation due to increasing loads. In the case of cyclic compressive loading, the model has been derived from experimental results obtained by other authors by considering the dependency of the cyclic variables with the damage level attained by the concrete. In the case of cyclic tension a simple model is adopted based on experimental observations. The main novelty of the proposed constitutive model lays in the fact that all the required input data can be obtained through the conventional monotonic compression and tension tests.
Nonlinear micro-mechanical analysis of masonry periodic unit cells
International Journal of Solids and Structures, 2016
Editorial
International Journal of Architectural Heritage, 2014
Editorial
International Journal of Architectural Heritage, 2009
Editorial
International Journal of Architectural Heritage, 2010
Simulation of in-plane shear test on masonry walls using micro modeling tecniques
Material Characterization and Micro-Modeling of a Historic Brick Masonry Pillar
International Journal of Architectural Heritage, Mar 4, 2016
ABSTRACT A masonry pillar composed of solid clay bricks, cement mortar and infill is extracted fr... more ABSTRACT A masonry pillar composed of solid clay bricks, cement mortar and infill is extracted from a historical structure and tested in concentric compression. It is subjected to cyclic and monotonic loads up to compressive failure. In parallel, samples are extracted from the pillar and are subjected to destructive tests. Non-destructive tests are performed on the pillar, as well. The properties of the constituent materials are critically examined and their role in the maximum load reached and the failure mode obtained are discussed. Finally, a finite element micro-model of the pillar is used for the simulation of the pillar test. The influence of the existing damage on the pillar is investigated using the model, resulting in a fair approximation of the global Young’s modulus, maximum load and the failure mode. Highlights ● A brick masonry pillar extracted from a historical building is tested in compression. ● Material samples extracted from the pillar are characterized by mechanical tests. ● A finite element micro-model of the pillar is used for the simulation of the compressive test. ● The effect of damage on the compressive strength of the pillar is numerically investigated.
A series of experimental tests involving in-plane shear loading of masonry walls is numerically s... more A series of experimental tests involving in-plane shear loading of masonry walls is numerically simulated using finite element detailed micro models. The experimental tests were performed on masonry walls composed of solid clay bricks and cement/lime mortar. The mechanical properties of the two constituent materials and the brick-mortar interface had been previously characterized. The walls were subjected to shear under varying levels of uni-form vertical pre-stress. The finite element models are created by modeling the bricks, mortar and the brick-mortar interface separately. In this manner the failure due to shear, tension or compression can be modelled in each component individually. Nonlinear constitutive laws to model cracking under tension and yielding under compression are used for the continuum elements modelling the units and the mortar. For the tension and shear failure of the interfaces a friction-tension cut off model is employed. Good agreement is found between the expe...
A set of experimental tests to determine the compressive strength of masonry stack prisms has bee... more A set of experimental tests to determine the compressive strength of masonry stack prisms has been numerically simulated using a combined plasticity-smeared crack constitutive law employed in three-dimensional analysis. Supported by an experimental campaign for the mechanical characterization of lime mortar masonry, a series of finite element analyses was performed in an attempt to assess the capacity of the model to reproduce the results obtained in terms of capacity, failure mode and global stiffness. The constitutive law used for the non-linear analysis of the masonry is a combination of a smeared cracking model in tension and a pressure dependent plasticity model in compression, which is capable of accounting for all failure mechanisms that may arise in concentric compression of masonry, both in the units and in the mortar. The purpose of this investigation is to establish whether a numerical approach based on the micro-modeling method is suitable for the simulation of the salient features encountered in masonry under compression as well as highlighting the main material properties necessary to be determined in order to properly model such experiments. The results are expanded upon through a parametric investigation.
For preserving existing structures to the extent possible, vibration-based damage detection techn... more For preserving existing structures to the extent possible, vibration-based damage detection techniques are gaining more attention. In specific, tracking the changes in a structure's natural frequencies employing the Principal Component Analysis (PCA) seems to be a promising technique. This paper presents an ongoing research for developing an approach for damage detection based on identifying the natural frequencies of the structure (via dynamic identification or monitoring) followed by applying PCA on the temporal variation of the identified natural frequencies. The processing of the dynamic monitoring data was carried out using a proposed semiautomatic algorithm able to identify and track the natural frequencies of the monitored structures and their changes over time. The algorithm was applied on one historical structure and two modern ones. PCA will to be carried out. The so far developed approach as a whole was applied on a steel structure model tested in lab. It was subjected to dynamic identification tests with and without damage. It was found that PCA applied to frequency variation seems to be a possible tool to know damages in structures. Nevertheless, the simplified point of view correlating directly the number of PCs with the damage importance seems to be not accurate. First results seem to indicate that the variance percentage explained by each of the principal components could be correlated with the kind of damages and the shake used to excite the structure.
The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathe... more The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathedral. This cathedral is an extraordinary historical construction dating back to the middle ages. The experimental modal parameters of the cathedral were identified using Ambient Vibration Testing (AVT). The cathedral numerical model was updated using the identified modal parameters. This updated model was then used to study the seismic response of the cathedral using non-linear static (pushover) analysis. A sensitively analysis was carried out to reveal the dependency of the seismic capacity on the input materials properties. To assess the seismic performance and the safety of the cathedral, the N2 method was employed. It was found that the cathedral is safe when subjected to the earthquakes expected in Mallorca Island.
The paper presents the current state of an on-going research aimed at characterizing the seismic ... more The paper presents the current state of an on-going research aimed at characterizing the seismic response of Mallorca cathedral. Mallorca cathedral is an audacious Gothic structure built in the island of Mallorca during 14 th -16 th centuries, characterized for its large dimensions and slender structural members. So far, experimental and numerical modal analysis, in addition to tentative model updating and seismic analysis, have been performed. The dynamic identification tests have been carried out by ambient vibration testing, while the frequency domain decomposition (FDD) technique has been used to obtain the modal parameters. A 3D Finite Element (FE) model has been used to determine the vibration modes. The model has been updated by modifying some structural parameters to improve the matching between experimental and numerical modal parameters. Once updated, the model has been utilized to study the seismic response of the cathedral using non-linear static pushover analysis. Conclusions on the possible collapse mechanisms and the seismic performance of the structure are presented.
This paper represents a continuation of a review on the seismic safety assessment of historical s... more This paper represents a continuation of a review on the seismic safety assessment of historical structures using some selected integrated investigation activities. In the first part of this review the dynamic investigation was presented. Here a focus is made on the updating of the numerical models used in the assessment phase and the used techniques in the seismic evaluation.
Assessment of seismic safety of historical structures is a challenging task because the informati... more Assessment of seismic safety of historical structures is a challenging task because the information available about the assessed structure is usually limited. Therefore, it is often necessary to exploit a number of integrated investigation activities to increase the level of knowledge about the historical structure under consideration. Thus, in the case of any need for providing the structure with strengthening intervention, this intervention will be a minimal and any unnecessary strengthening operations will be avoided. This paper presents a literature review carried out to cover the current state-of-the-art of a number of investigation activities carried out integrally for the seismic safety assessment of historical structures. It is presented in two parts. In this first part, the covered topic is the dynamic investigation of historical structures which includes the dynamic identification tests, the dynamic monitoring, and the modal parameters identification methods with the classical and the advanced techniques like the peak picking and the stochastic subspace identification.
The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathe... more The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathedral. This cathedral is an extraordinary historical construction dating back to the middle ages. The experimental modal parameters of the cathedral were identified using Ambient Vibration Testing (AVT). The cathedral numerical model was updated using the identified modal parameters. This updated model was then used to study the seismic response of the cathedral using non-linear static (pushover) analysis. A sensitively analysis was carried out to reveal the dependency of the seismic capacity on the input materials properties. To assess the seismic performance and the safety of the cathedral, the N2 method was employed. It was found that the cathedral is safe when subjected to the earthquakes expected in Mallorca Island.
Contribution of inspection techniques to the assessment of historical structures
Article
The presented research aimed at studying the dynamic behavior of Mallorca cathedral (Mallorca Isl... more The presented research aimed at studying the dynamic behavior of Mallorca cathedral (Mallorca Island, Spain) under ambient sources of vibration and seismic events. The cathedral is one of the greatest built masonry structures worldwide. It is characterized for its audacious dimensions and slender structural members. Because of it, the study of its dynamic behavior is a clear concern. The cathedral dynamic properties were firstly identified using ambient vibration testing. Afterwards, a dynamic monitoring system was implemented to continuously measure, record, and wirelessly transfer the acceleration records without having to set up an activating threshold. This monitoring type was implemented because of the low seismic intensity of Mallorca Island with a basic ground acceleration of only 0.04 g according to the Spanish seismic standard. The continuous monitoring allowed for capturing some seismic events and some drops in the natural frequencies were noticed because of a breathing crack effect. Using both ambient vibration testing and continuous monitoring system, global modes could be more accurately identified than more local ones. The identification of the global modes was more attainable than in the case of more local ones. The temperature was a more influential environmental parameter than humidity and wind for all of the identified modes except for one more directly depended on wind.
The paper presents the results of experimental research on the structural behavior of dry joint m... more The paper presents the results of experimental research on the structural behavior of dry joint masonry. The most relevant experimental results concern the strength response of stone dry joint masonry walls subjected to in-plane combined compressive and shear loading. Significant features of the structural behavior shown by the walls are discussed and conclusions on their ultimate capacity and observed failure mechanisms are addressed. Complementarily, the application of an existing numerical model, stemming from plasticity and based on a micromodeling strategy, is also presented and discussed with regard to its capacity to simulate the obtained experimental results. The model was calibrated with data collected from complementary tests carried out on specimens and prisms made of the same type of stone. Finally, the usage of a simplified method of analysis based on a continuum of diagonal struts is also addressed.
Non Linear Response of Masonry Wall Structures Subjected to Cyclic and Dynamic Loading
Engineering Structures, Jan 1, 2011
The assessment of the dynamic or seismic performance of complex structures often requires the int... more The assessment of the dynamic or seismic performance of complex structures often requires the integration in the time domain of the structural equation of motion in the frame of a nonlinear analysis. Although sophisticated methods have been developed for the nonlinear analysis of masonry wall structures, including the macro- and micro-modeling approaches, these require large computational effort still limiting the extent and complexity of the structures analyzed. This paper presents an alternative method based on the Generalized Matrix Formulation for masonry skeletal structures and load bearing wall systems, which has been proved as an efficient formulation for the analysis of the strength capacity of these kinds of structures (Roca et al. (2005) [17]). The basic formulation has been complemented with a uniaxial cyclic constitutive model for masonry and a time integration scheme. The ability of the resulting approach to predict the nonlinear dynamic response of masonry structures is shown through its application to the time domain analysis of an experimental scale masonry building with available experimental results on its dynamic response.
Engineering structures, Jan 1, 2008
A constitutive model for concrete subjected to cyclic loadings in both compression and tension is... more A constitutive model for concrete subjected to cyclic loadings in both compression and tension is presented. The proposed model is intended to provide improvements on modelling the cyclic behaviour of concrete structures in the context of computational programs based on a smeared crack approach. Particular emphasis has been paid to the description of the strength and stiffness degradation produced by the load cycling in both tension and compression, the shape of unloading and reloading curves and the transition between opening and closing of cracks. Two independent damage parameters in compression and in tension have been introduced to model the concrete degradation due to increasing loads. In the case of cyclic compressive loading, the model has been derived from experimental results obtained by other authors by considering the dependency of the cyclic variables with the damage level attained by the concrete. In the case of cyclic tension a simple model is adopted based on experimental observations. The main novelty of the proposed constitutive model lays in the fact that all the required input data can be obtained through the conventional monotonic compression and tension tests.
Nonlinear micro-mechanical analysis of masonry periodic unit cells
International Journal of Solids and Structures, 2016
Editorial
International Journal of Architectural Heritage, 2014
Editorial
International Journal of Architectural Heritage, 2009
Editorial
International Journal of Architectural Heritage, 2010