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- New finite element to model bond–slip with steel strain effect for the analysis of reinforced concrete structuresPublication . Santos, José; Henriques, António AbelThe influence of steel strain in bond–slip relationship has been the subject of recent literature, especially steel strain after yielding. This paper presents a new bond element for finite element packages which performs the bond–slip relationship, including steel strain effect. The developed element consists of an orthotropic four-node plane stress element whose constitutive material laws were changed. In order to verify the accuracy of this element several 2D numerical results were compared with experimental data. The results obtained with this element showed the need for its use to achieve good results and the rel evance of steel strain effect on bond–slip relationship, especially in tension elements.
- Vibrações induzidas por peões em escadas metálicasPublication . Andrade, Pedro; Santos, José; Escórcio, Patrícia
- Strength and ductility of damaged tempcore rebarsPublication . Santos, José; Henriques, A. AbelThe Tempcore rebars behaviour results from the interaction of the three layers that compose them, with different initial stresses. Therefore, their mechanical properties study is important for the understanding of the rebar overall behaviour. In this paper it is presented and discussed the results of hardness, strength and ductility obtained in tensile and hardness tests of several samples from Tempcore rebars (with high ductility) with various damage levels. The assessment of strength and ductility in locally damaged rebars concluded that the ultimate strain decrease is the main anomaly, mainly due to the hardening of steel that allows overcoming the yield stress decrease until damages of 20%.
- Span-to-depth ratio limits for RC continuous beams and slabs based on MC2010 and EC2 ductility and deflection requirementsPublication . Santos, José; Henriques, António AbelIn the design of reinforced concrete structures several limit states are usually verified using simplified methods instead of using complex direct calculation. Span-to-depth ratio limits are applied for deflection control. In the same way, a redistribution factor and the relative depth of the compression zone are applied for the required ductility, but this is not enough. In fact, specific span-to-depth ratio limits, which are developed in this paper, should also complement the conditions referred to here. A numerical study is developed to compute the deflection ductility index of a wide range of continuous beams (or one-way slabs) considering as ultimate point when the rotation capacity (given by MC2010 and EC2) is achieved. From the boundary between fragile and ductile failures, the new span-to-depth ratio limits for the required ductility are defined and compared with the existing similar limits for deflection control. The results indicate that: (i) for normal strength concrete (up to 50 MPa), the ductility limit is more restrictive than the deflection limit when the redistribution factor δ is lower than 0.9, being always more restrictive for high strength concrete; (ii) for the current building beams, the slenderness used (10 < l/d < 20) allows ductile fail ures, while for typical building slabs (low reinforcement ratio, but high redistribution), the slenderness should be l/d ≤ 20; (iii) the conditions of MC2010 and EC2 to use plastic analysis without any direct check of the rotation capacity are actually incomplete and need to be revised. The new span-to-depth ratio limits proposed in this paper, which satisfy both ductility and deflection requirements, depend on the redistribution factor, characteristic compressive strength of concrete and total mechanical reinforcement ratio
- Direct integration methods versus modal superposition method, on predicting staircases vibrationsPublication . Andrade, Pedro; Santos, José; Escórcio, PatríciaThe majority of Finite Element software’s present two different solutions methods to perform time history analysis of the equations of motion due to dynamic (time-varying) loads: Direct Integration and Modal Superposition. This paper aims to assess which method should be employed in the design of modern flexible staircases, to more efficiently predict human induced vibrations. This was verified by estimating vibrations on a real staircase using the two time domain analysis methods and, then, comparing with vibrations experimentally measured. The results indicate that Direct Integration could yield to overestimated responses due to the limited capacity, as the vibration modes increase, of FE numerical models to realistic predict natural frequencies and modal shapes of a real structure. Therefore, Modal Superposition is suggested to be used for design routines, excluding, for the same reason, the vibration modes with higher frequency content. © 2020 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo Keywords: Modal Superposition; Direct Integration; Duhamel Integral; Human Walking Vibrations; Flexible Staircases. * Corresponding author. Tel.: +351 291 705 197. E-mail address: jmmns@fe.up.pt Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000 www.elsevier.com/locate/procedia 2452-3216 © 2020 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the European Structural Integrity Society (ESIS) ExCo 1st Virtual European Conference on Fracture Direct Integration Methods versus Modal Superposition Method, on Predicting Staircases Vibrations Pedro Andradea , José Santosb,c,*, Patrícia Escórciob a University of Madeira, 9020-105 Funchal, Portugal b University of Madeira, Faculty of Exact Sciences and Engineering, Department of Civil Engineering and Geology, 9020-105 Funchal, Portugal c CONSTRUCT-LABEST, Faculty of Engineering (FEUP), University of Porto, Portugal Abstract The majority of Finite Element software’s present two different solutions methods to perform time history analysis of the equations of motion due to dynamic (time-varying) loads: Direct Integration and Modal Superposition. This paper aims to assess which method should be employed in the design of modern flexible staircases, to more efficiently predict human induced vibrations. This was verified by estimating vibrations on a real staircase using the two time domain analysis methods and, then, comparing with vibrations experimentally measured. The results indicate that Direct Integration could yield to overestimated responses due to the limited capacity, as the vibration modes increase, of FE numerical models to realistic predict natural frequencies and modal shapes of a real structure. Therefore, Modal Superposition is suggested to be used for design routines, excluding, for the same reason, the vibration modes with higher frequency content.
- Application of the effective impulse approach to stairsPublication . Andrade, Pedro; Santos, José; Escórcio, PatríciaOne of the most commonly used simplified methods for predicting man induced vibrations in floors with high fundamental frequencies is the Effective Impulsive approach, first developed by the ARUP's company and later modified by the design guide SCI P354. Since the Effective Impulse approach was designed to be used in floors, its use in stairs can be arguable. To better understand the effectiveness of this method in stairs, in this paper are experimentally measured vibrations on a staircase with a poor dynamic behavior and then compared to the vibrations predicted using the Effective Impulse approach. The results indicate that this approach can be used, especially in the stair descends. The serviceability of the analyzed staircase was also verified by comparing the measured and predicted vibrations with the acceptable limits proposed by various authors and design guides.
- Pre-design of laterally supported stair stepsPublication . Santos, José; Andrade, Pedro; Escórcio, PatríciaIt is becoming increasingly common to design monumental staircases and their steps with elevated stiffness and low mass, obtaining high natural frequencies, off the range of frequencies that are excitable by pedestrians. However, this sometimes leads to unacceptable levels of vibration, with impulsive responses. In many cases the dynamic behaviour of steps is almost independent from the rest of the staircase, causing a phenomenon de signated as local vibrations, which could be much more severe than the global vibrations of the staircase. In order to avoid this problem, this paper presents a simplified expression to pre-design stair steps which guarantee that excessive vibrations will not occur, without the need to perform a dynamic analysis. The ex pression was deduced based on the results of an experimental campaign, several numerical analyses and a theoretical analysis. During this study it was necessary to define an acceptable limit of vibrations specific for this type of vibration, which affects mainly the feet of pedestrians. The expression deduced is easy to apply because it depends only of vertical stiffness of the step. Finally, the pre-design expression is also applied to the staircase used in the experimental campaign, and it was concluded that it would be easy to avoid excessive vibrations, with a negligible cost increase.
- Elemento finito para modelar a relação aderência-escorregamento incluindo o efeito da extensão do aço na análise de estruturas de betão armadoPublication . Santos, José; Henriques, António AbelA influência da extensão do aço na relação tensão de aderência-escorregamento tem vindo a ser reconhecida na literatura recente, especialmente para extensões no aço superiores à extensão de cedência. Neste artigo apresenta-se a formulação para um novo elemento finito de interface entre o betão e o aço que tem em conta a extensão deste último. A interface desenvolvida consiste num elemento ortotrópico de estado plano de tensão com quatro nós, cujas leis constitutivas são modificadas. O elemento foi aplicado em diversos modelos numéricos de elementos finitos para comparação com resultados experimentais. Os resultados obtidos mostram a relevância da extensão do aço na relação tensão de aderência-escorregamento, especialmente nos elementos tracionados.
- Using BIM to improve building energy efficiency: a scientometric and systematic reviewPublication . Pereira, Vítor; Santos, José; Leite, Fernanda; Escórcio, PatríciaThe Architecture, Engineering, Construction, and Operations (AECO) sector is responsible for a great pro portion of the global energy consumption and associated environmental impacts. On this front, and from a sustainability improvement perspective, the use of Building Information Modelling (BIM) capabilities could represent an opportunity to improve these impacts in all steps of a building’s life. The main purpose of the current paper is to identify the areas in which BIM technology can or already is playing a role in improving building efficiency, helping AECO sector stakeholders in reducing environmental impacts. In the current paper, the impact of using BIM to enhance the building energy efficiency is explored through a scientometric analysis and a systematic literature review. There is a high interest among the scientific community in these fields, given the recent rise in publications and citation numbers. Moreover, there is a lack of interoperability between BIM and energy analysis tools, a high potential for integrating BIM with other technologies, such as thermography, Geographic Information Systems (GIS) and monitoring, and a very positive impact from the use of BIM in the optimisation of construction solutions which allow energy savings in the AECO sector.
- Old bridges in Madeira Island: identification and diagnosticPublication . Santos, José; Rodrigues, FábioIn Madeira Island there are several old bridges mostly of stone masonry and some of concrete, which are a valuable historical heritage, wand hich is important to know and maintain. With this in mind, this paper shows the results of a survey study including diagnostic of a wide range of old bridges in Madeira. It was observed that the great part of these bridges is of stone masonry sometimes strengthened by concrete, and that they have some essentially non-structural anomalies, mainly the presence of vegetation. So, they are in reasonable condition, being important the current maintenance works