Seismic Behavior of Colliding Buildings, Incorporating Soil-structure Interaction and Accounting for Variability in Structural Parameters, Soil Parameters, and Seismic Action

Pounding between buildings that are not sufficiently separated has been observed several times during earthquakes. This destructive impact may severely damage the structure and lead to its collapse. Although it is impossible to completely eliminate such losses, measures can be taken to minimize them. This article investigates the effect of the variability of structural parameters, soil parameters, and seismic action on the seismic response of two colliding buildings, taking the soil-structure interaction (SSI) into account. Two adjacent structures closely separated, modeled as inelastic lumped mass systems with different structural characteristics, were considered in this study. Both structures were modeled in the analysis using multi-degree-of-freedom (MDOF) systems, and the pounding was simulated using the modified linear viscoelastic model. The analysis was conducted in two cases: probabilistic analysis and deterministic analysis. Probability curves were established to analyze the effect of the variability of the parameters on the responses of the two colliding buildings. The comparison between the two analyses indicates that the probabilistic analysis is more precise than the deterministic analysis. It has been indicated that taking into account the variability of structural parameters, soil parameters, and seismic action is efficient in determining the realistic behavior of colliding buildings. Additionally, pounding is more critical in the case of buildings founded on very soft soil, followed by those on soft soil, then on hard soil, and finally on rocky soil

Contribution à la Proposition d’une Nouvelle Approche de Calcul Sismique des Structures en Interaction avec le Sol (N2-ISS)

The purpose of this article is to contribute to the study of the seismic behavior of structures interacting with the ground and to offer new tools for the treatment of relevant problems, oriented towards the new seismic design philosophy of structures: the design performance-based design. The issue is part of the proposal for simplified models to address a complicated problem such as soil-structure interaction (ISS). The nonlinear behavior of the structure is determined by a capacitive approach based on the seismic performance such as the N2 method proposed by Peter Fajfar. In its original version, this method considers that the structure is fixed at its base, neglecting the ISS. Our contribution will be to make some modifications to this approach to introduce the effect of the soil on the nonlinear response.The purpose of this article is to contribute to the study of the seismic behavior of structures interacting with the ground and to offer new tools for the treatment of relevant problems, oriented towards the new seismic design philosophy of structures: the design performance-based design. The issue is part of the proposal for simplified models to address a complicated problem such as soil-structure interaction (ISS). The nonlinear behavior of the structure is determined by a capacitive approach based on the seismic performance such as the N2 method proposed by Peter Fajfar. In its original version, this method considers that the structure is fixed at its base, neglecting the ISS. Our contribution will be to make some modifications to this approach to introduce the effect of the soil on the nonlinear responseL’objectif de cet article est de contribuer à l’étude du comportement sismique des structures en interaction avec le sol et d’offrir de nouveaux outils pour le traitement de problèmes pertinents, orientés vers la nouvelle philosophie de conception parasismique des structures : la conception basée sur la performance (performance-based design). La problématique s’inscrit dans le cadre de proposition de modèles simplifiés afin d’aborder un problème compliqué tel que l’interaction sol-structure (ISS). Le comportement non linéaire de la structure est déterminé par une approche capacitive basée sur la performance sismique telle que la méthode N2 proposée par P. Fajfar. Dans sa version originale, cette méthode considère que la structure est encastrée à sa base, négligeant ainsi l’ISS. Notre contribution sera d’apporter quelques modifications à cette approche pour introduire l’effet du sol sur la réponse non linéaire

Approche probabiliste dans la détermination des courbes de vulnérabilité des structures en génie civil

In the context of performance-based earthquake engineering (PBEE), a challengingtask for structural engineers is to provide performance and risk assessment for structures orsoil-structure interaction (SSI) systems. In order to fulfill this task successfully, all relevantsources of aleatory and epistemic uncertainties must be accounted for during the designprocess. Thus, proper methods are required for the study of uncertainty propagation frommodel parameters describing the structure, the soil, and the applied loads to structuralresponses by defining some performance limit states. The objective of this thesis is tocontribute to the study of the seismic behavior of structures interacting with soil andprovide new tools for the treatment of relevant issues facing the new philosophy of seismicdesign of structures: performance-based design. The objective of this thesis is to contributeto the study of the seismic behavior of structures interacting with soil and provide newtools for the treatment of relevant issues facing the new philosophy of seismic design ofstructures: (performance-based design). This research structure this doctoral work. Theissue is part of proposed simplified models to address a complicated problem such as soilstructureinteraction (SSI). The nonlinear behavior of the structure is determined by acapacitive approach based on the seismic performance as N2 method proposed by P.Fajfar. In its original version, this method considers that the structure is fixed at its base,thus neglecting the ISS. The new proposed method called N2-SSI is an extension of the N2method. To our knowledge, there are no studies that have joined the SSI ISS in this type offormalism. The proposed approach is validated and compared with time history analysis,Building Seismic Safety Council (BSSC) method (NEHRP, 2003), and a method proposedby Aviles and Perez-Rocha (2003). The results obtained showed that the responsedisplacement of the structure was fairly close in the four methods.The fragility curves are established taking into account the effects of the ISS anddifferent uncertainty sources: the load (input ground motion), the soil, the structure and theSSI (impedances, ...). Epistemic uncertainty was investigated through comparison betweentwo different approaches in assessing damage states (Park and Ang and Risk-UE). Thestudy also resulted in a preliminary characterization of the seismic risk in a part of the Orancity, where geological and geotechnical characteristics were available. This study allowedthe mapping of the damage and the study of the seismic vulnerability of buildings.Dans le contexte du calcul sismique basé sur la notion de performance, lesingénieurs se trouvent confrontés à une tâche difficile pour estimer la performance etévaluer les risques des systèmes sol-structure en interaction. Afin d’accomplir cette tâcheavec succès, toutes les sources d'incertitudes aléatoires et épistémiques doivent être prisesen compte au cours du processus de conception. Ainsi, des méthodes appropriées sontnécessaires pour l'étude de la propagation de l'incertitude des paramètres du systèmedécrivant la structure, le sol, et les charges appliquées aux réponses structurelles endéfinissant des états limites de performance. L’objectif de cette thèse est de contribuer àl’étude du comportement sismique des structures en interaction avec le sol et d’offrir denouveaux outils pour le traitement de problèmes pertinents, orientés vers la nouvellephilosophie de conception parasismique des structures : la conception basée sur laperformance (performance-based design). Cet axe de recherche structure ce travail dedoctorat. La problématique s’inscrit dans le cadre de proposition de modèles simplifiés afind’aborder un problème compliqué tel que l’interaction sol-structure (ISS). Lecomportement non linéaire de la structure est déterminé par une approche capacitive baséesur la performance sismique telle que la méthode N2 proposée par P. Fajfar. Dans saversion originale, cette méthode considère que la structure est encastrée à sa base,négligeant ainsi l’ISS. Il s'agit d'une extension de la méthode N2 et que nous appelleronsN2-ISS. A notre connaissance, il n'existe pas d'études qui ont intégré l'ISS dans ce type deformalisme. Pour examiner la validité et la fiabilité du modèle présenté, une analysecomparative a été faite entre l'approche que nous proposons et trois autres méthodes: 1) laméthode introduite dans le code BSSC 1997, 2) la méthode proposée par Avilès & Perez–Rocha (2003) ainsi que 3) la méthode dynamique temporelle non linéaire. Les résultatsobtenus ont montré que la réponse en déplacement de la structure était assez proche dansles quatre méthodes.Les courbes de fragilité sont établies en tenant compte des effets de l’ISS et desincertitudes associées au chargement (mouvement du sol), aux propriétés de la structure,du sol, et de la fondation (impédances, ...). L’incertitude épistémique est égalementconsidérée de manière indirecte suite à la comparaison entre deux procédures d'évaluationdes états d’endommagements (Méthode de Park & Ang et Méthode de RISK-UE). L'étudea abouti aussi à une caractérisation préliminaire du risque sismique dans une partie de laville d'Oran dont les caractéristiques géologiques et géotechniques étaient disponibles.Cette étude a permis la cartographie du dommage et d'étudier la la vulnérabilité sismiquedes bâtiments

Sensitivity Analysis of Uncertain Material RC Structure and Soil Parameters on Seismic Response of Soil-Structure Interaction Systems

In seismic performance based design context, engineers are faced to a difficult task to estimate the response of soil-structure interaction (SSI) systems. To accomplish this task successfully, all sources of random and epistemic uncertainties should be taken into account. However, the uncertain parameters have not the same influence on the model response; a sensitivity analysis is therefore required. This article treats the two following aspects: the first one is to perform a sensitivity analysis on all the parameters in order to study their influence on the structural response. The uncertainties effect is done by studying the sensitivity of the maximum structure displacement towards the used materials parameters variation (fc’, εc0, εcu, Es, fsy, α, εsu, A, ξ) and soil properties (ξg, ν) on the SSI seismic response. This study consists of determining, quantifying and analyzing how the outputs of the N2-SSI model are affected by input variables fluctuations. The second aspect is analysing the SSI system response by considering the correlation between the parameters (shear wave velocity and soil damping) and the influence of the lack knowledge of the uncertainties due to this correlation. The results of the sensitivity analysis indicate that the response of the structure is very sensitive to the concrete and steel parameters for larger values of the shear wave velocity. While, the soil damping and Poisson's ratio in the case of soil with shear wave velocity of 90 m/s, are the main inputs with the greatest influence on the maximum displacement output

Orchestration under Security Constraints

International audienceAutomatic composition of web services is a challenging task. Many works have considered simplified automata models that abstract away from the structure of messages exchanged by the services. For the domain of secured services (using e.g. digital signing or timestamping) we propose a novel approach to automated composition of services based on their security policies. Given a community of services and a goal service, we reduce the problem of composing the goal from services in the community to a security problem where an intruder should intercept and redirect messages from the service community and a client service till reaching a satisfying state. We have implemented the algorithm in AVANTSSAR Platform and applied the tool to several case studies

The Impact of Coupling Signaling Protocols and Codecs Scheme in Achieving VoIP Quality

VoIP is short for voice over Internet protocol and is also known as IP telephony, VoIP is a modern technology that enables us to make voice calls using IP networks. Therefore, VoIP can be achieved on any data network that uses IP, like the Internet, Intranets and Local Area Networks. In traditional network data is always fragmented into many data packets then transmitted independently. As the result packets arrived out of order at the destination ,in e-mail applications  and  downloading document this disorder is   represent no problem  since the packets will be reassembled in the correct order  when they all has arrived at the destination. VoIP uses different signaling protocols and Coding schemes, choosing the inappropriate coding scheme for one of the signaling protocols leads to poor Quality of Service (QoS). This paper aims to specify the best combination of coding scheme and signaling protocols and Measure the QoS parameters (jitter, end to end delay, and throughput) of transmission protocol

Synthèse et compilation de services web sécurisés

Automatic composition of web services is a challenging task. Many works have considered simplified automata models that abstract away from the structure of messages exchanged by the services. For the domain of secured services (using e.g. digital signing or timestamping) we propose a novel approach to automated composition of services based on their security policies. Given a community of services and a goal service, we reduce the problem of composing the goal from services in the community to a security problem where an intruder should intercept and redirect messages from the service community and a client service till reaching a satisfying state. We have implemented the algorithm in Avantssar Platform and applied the tool to several case studies. Then we present a tool that compiles the obtained trace describing the execution of a the mediatorinto its corresponding runnable code. For that we first compute an executable specification as prudent as possible of her rolein the orchestration. This specificationis expressed in ASLan language, a formal language designed for modeling Web Services tied with security policies. Then we can check with automatic tools that this ASLan specification verifies some required security properties such as secrecy and authentication.If no flaw is found, we compile the specification into a Java servlet that can be used by the mediator to lead the orchestration.La composition automatique de services web est une tâche difficile. De nombreux travaux ont considérés des modèles simplifiés d'automates qui font abstraction de la structure desmessages échangés par les services. Pour le domaine des services sécurisés (par exemple utilisantla signature numérique ou l'horodatage), nous proposons une nouvelle approche pour automatiserla composition des services basés sur leurs politiques de sécurité.Étant donnés, une communauté de services et un service objectif, nous réduisons le problème de lasynthèse de l'objectif à partir des services dans la communauté à un problème de sécurité, oùun intrus doit intercepter et rediriger les messages depuis et vers la communauté de serviceset un service client jusqu'à atteindre un état satisfaisant pour le dernier.Nous avons implémenté notre algorithme dans la plateforme de validation du projet AVANTSSARet nous avons testé l'outil correspondant sur plusieurs études de cas. Ensuite, nous présentons un outil qui compile les traces obtenues décrivant l'exécution d'un médiateur versle code exécutable correspondant.Pour cela nous calculons d'abord une spécification exécutable aussi prudente que possible de son rôledans l'orchestration. Cette spécification est exprimé dans la langue ASLan, unlangage formel conçu pour la modélisation des services Web liés à des politiques de sécurité.Ensuite, nous pouvons vérifier avec des outils automatiques que la spécification ASLan obtenue vérifie certainespropriétés requises de sécurité telles que le secret et l'authentification.Si aucune faille n'est détectée, nous compilons la spécification ASLan vers une servlet Java qui peut êtreutilisé par le médiateur pour contrôler l'orchestration

Effects of nitrogen source, rate and foliar application on some leaf mineral nutrient contents and yield of “Sinnari” sweet oranges (Citrus sinensis L.) in the River Nile State, Sudan

      Sweet orange production in the Sudan is characterized by low yield and poor fruit quality. This research was aimed at determining the effects of nitrogen source, rate and foliar application on some leaf mineral nutrient content and yield of “Sinnari” sweet oranges in  the River Nile State during 2010/11 and 2011/12. Nitrogen sources were urea (100%), sheep manure (SM) (100%), or a combination of them (50% each), beside Wuxal foliar fertilizer. Nitrogen rates were 0, 43 and 86 kg N/ha. Treatments were arranged in a randomized complete block design with three replicates and 2 trees/plot. Results showed that nitrogen sources and rates were effective in increasing leaf nitrogen content and the highest values were obtained by the application of 86 kg N/ha using urea (100%) or a combination of urea and sheep manure. Application of Wuxal foliar fertilizer resulted in a significant increase of Zn and Fe leaf contents and total yield. Nitrogen source had significant effects on yield components and total yield. The highest values were obtained by a combination of urea and sheep manure or 100% urea, and the lowest values were recorded for 100% sheep manure. Nitrogen rate of 86 kg N/ha resulted in the highest yield components and total yield. It is recommended to fertilize sweet orange trees in the River Nile State with a combination of urea and sheep manure at the rate of 86 kg N/ha (12.4 kg SM/tree and 0.5 kg urea/tree) in addition to Wuxal foliar fertilizer

Current status of sweet orange (Citrus sinensis L.) orchards in the River Nile State, Sudan

ABSTRAC     Production of sweet oranges in the Sudan does not cover domestic needs and sweet oranges are currently imported from Egypt, Iran and South Africa to satisfy the increasing demand. Hence, there is a need to investigate factors involved in the decline of sweet orange trees in one of the most important States for orange production in the Sudan. This research aims to study and evaluate different agronomic practices contributing to the prevailing sweet orange performance in the River Nile State, Sudan. A questionnaire and interviews with 120 sweet orange growers from Ketiab, Zeidab and Gandato citrus projects indicated that 75.8% of the farmers have orchards less than 2.9 ha. Low yielding cultivars such as “Sinnari”, the local selection (Baladi), Hamlin and Nori 16 dominate in the areas, 96.7% of the trees were budded on sour orange rootstocks, 85.8% of the seedlings were budded in private nurseries using bud wood collected from non-certified mother trees from private orchards. All sweet oranges were grown with other fruit species in 100% of the orchards, 80.8% used flat surface irrigation. There is no fixed fertilizer program. The type and quantity of chemical and organic fertilizers varied with different growers. No foliar fertilizers were used and nutrient deficiencies of Zn, Fe and Mn were observed in most orchards. Extension services for citrus production are highly needed for improvement of yield and quality of sweet oranges in the River Nile Stat