1,721,113 research outputs found
Stick-IT: A simplified model for rapid estimation of IDR and PFA for existing low-rise symmetric infilled RC building typologies
No full textThe prediction of seismic performances of buildings in terms of engineering demand parameters EDP, such as interstorey drift ratios IDR and peak floor accelerations PFA, represents a fundamental step towards the assessment of potential direct economic losses. This paper proposes a simplified model for the rapid assessment of EDPs in infilled moment resisting frames subjected to seismic loadings suitable for large scale assessment studies. The proposed model, named Stick-I (Stick model for Infilled frames), is a multi-degree of freedom MDOF system consisting of a series of lumped masses connected by means of nonlinear shear link elements. The shear link behavior is suitably calibrated adopting a multi-objective Genetic Algorithm procedure that employs the results of nonlinear cyclic pushover analyses performed on refined nonlinear FEM. Based on the regression study performed on a suitably generated Stick-I model database, a more general Stick-IT model, representative of RC Infilled frame Typologies of assigned storey number and dimensions in plan, is introduced. Simplified formulas for the definition of Stick-IT model are proposed depending on low-level information data that can be easily retrieved from rapid on-site surveys or remote sensing techniques. Both Stick-I and Stick-IT models are validated comparing the results of NRHA performed on refined FEMs with the results obtained adopting the simplified models and good agreement in terms of maximum EDP values and distribution along the building height is obtained. The typological Stick-IT model, which is defined as a function of few geometric and mechanical parameters, can be easily applied for simplified evaluation of expected response for building typologies. Hence, it can also be usefully employed for assessment of direct losses at the large scale, with a significant reduction in computational burden with respect to more refined methods
Performance comparison of dual connectivity and hard handover for LTE-5G tight integration
No full textCommunications at frequencies above 10 GHz (the mmWave band) are expected to play a major role for the next generation of cellular networks (5G), because of the potential multi-gigabit, ultra-low latency performance of this technology. mmWave frequencies however suffer from very high isotropic pathloss, which may result in cells with a much smaller coverage area than current LTE macrocells. High directionality techniques will be used to improve signal quality and extend coverage area, along with a high density deployment of mmWave base stations (BS). However, when propagation conditions are hard and it is difficult to provide high quality coverage with mmWave BS, it is necessary to rely on previous generation LTE base stations, which make use of lower frequencies (900 MHz - 3.5 GHz), which are less sensitive to blockage and experience lower pathloss. In order to provide ultra-reliable services to mobile users there is a need for network architectures that tightly and seamlessly integrate the LTE and mmWave Radio Access Technologies. In this paper we will present two possible alternatives for this integration and show how simulation tools can be used to assess and compare their performance
Seismic fragility curves for infilled RC building classes considering multiple sources of uncertainty
No full textThis paper presents damage fragility curves derived through an analytical approach for reinforced concrete building classes representative of the existing Italian building stock. Fragility curves are generated by adopting a fully probabilistic framework that relies on a cloud-based approach employing real ground motion records and allows accounting and propagating the main sources of uncertainty. The seismic performance of masonry-infilled reinforced concrete frames is estimated via nonlinear time-history analyses performed via a simplified multi-degree-of-freedom model named STICK, in which the behavior of the frame is concentrated at the storey level. Thanks to the versatility of the adopted analytical model and its reduced computational burden, the effect of the main uncertainties that are typically neglected or only partially considered during the generation of analytical fragility curves is accounted for within the framework. Specifically, the inter-building, intra-building, and record-to-record variabilities, as well as variability related to the definition of the building damage level are explicitly considered. Fragility curves are developed for Damage States compatible with the EMS98 scale as a function of the peak ground acceleration for building classes defined adopting as main attributes the number of storeys, the age of construction, the design level, and the typology of infill panels. The proposed fragility curves are also compared with existing empirical ones showing a good agreement that confirms the validity of the proposed framework
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