José Miguel Castro

Attack Efficacy in Volleyball: Elite Male Teams

The goal was to identify performance indicators predicting attack efficacy in volleyballs game phase denominated Complex II, i.e., the counter-attack. 28 games from the 2007 Mens World Cup were analyzed. Attack efficacy was predicted by three primary variables: Attack tempo, Attack type, and Number of blockers. Power attack and Attack tempo 1 increased the probability of an Attack point. The supremacy of Attack tempo 3 and the high frequency of Two blockers and Three blockers reflected the difficulty of efficient attack during Complex II. Despite unfavourable conditions, attackers managed to execute Power attacks in the majority of the situations, and score a high frequency of Attack points.

Analysis of the Attack Tempo Determinants in Volleyball’s Complex II – a Study on Elite Male Teams

This study aims to analyse possible determinants that might predict the attack tempo in the Volleyball’s complex II. A total of 881 actions were analyzed from 28 games of the national male teams presented in the World Cup 2007. A multinomial logistic regression was applied, with the level of significance determined in α=0.05. The variables dig type, dig efficacy and setting zone demonstrated predictive power of the attack tempo. The dig without all attack options and the dig with fall decreased the probability of quicker attack tempos. The higher frequency of the dig without all attack options is, perhaps, an explanation to the high values of the non acceptable setting zone, whose occurrence promotes a slower attack organization. In this sense, the increasing of the dig efficacy and stabilization of the dig type will improve the dig action to acceptable and excellent setting zones, which will increase the use of quicker attack tempos.

On the quantification of local deformation demands and adequacy of linear analysis procedures for the seismic assessment of existing steel buildings to EC8-3

The application of performance-based design and assessment procedures requires an accurate estimation of local component deformation demands. In the case of steel moment-resisting frames, these are usually defined in terms of plastic rotations. A rigorous estimation of this response parameter is not straightforward, requiring not only the adoption of complex nonlinear structural models, but also of time-consuming numerical integration calculations. Moreover, the majority of existing codes and guidelines do not provide any guidance in terms of how these response parameters should be estimated. Part 3 of Eurocode 8 (EC8-3) requires the quantification of plastic rotations even when linear methods of analysis are used. Therefore, the aim of the research presented in this paper is to evaluate different methods of quantifying local component demands and also to answer the question of how reliable are the estimates obtained using the EC8-3 linear analysis procedures in comparison to more accurate nonlinear methods of analysis, particularly when the linear analysis applicability criterion proposed by EC8-3 is verified. An alternative methodology to assess the applicability of linear analysis is proposed which overcomes the important limitations identified in the EC8-3 criterion.

A Critical Review of European and American Provisions for the Seismic Assessment of Existing Steel Moment-Resisting Frame Buildings

ABSTRACT The publication of Part 3 of Eurocode 8 (EC8-3), dedicated to the seismic assessment of existing buildings, took place a decade ago. However, its application in engineering practice has been limited. Moreover, no studies have been conducted regarding the application of EC8-3 to steel structures. In this paper, a critical review and practical application of EC8-3 and ASCE41-13 are carried out. Issues related to the definition of the performance requirements, compliance criteria, and the consistency of the analysis procedures proposed by both standards are identified. Conceptual differences between both documents are highlighted, and several inconsistencies in EC8-3 are discussed.

Probabilistic Fatigue Crack Initiation and Propagation Fields Using the Strain Energy Density

The fatigue crack growth (FCG) has been widely studied by the scientific community. There are several proposed FCG models, the best known being the Paris relation. The fatigue crack initiation and propagation have been studied separately, however, researchers have made an effort to study the relationship between these two fatigue phenomena. In this sense, several fatigue crack growth models based on local approaches have been proposed, the UniGrow model being well-known. The fatigue crack growth process is assumed a succession of crack re-initiations considering a certain elementary material size. Recently, Huffman developed a strain energy density based on Walker-like stress life and fatigue crack growth behavior. In this paper, the Huffman model based on local strain energy density is used to predict the fatigue crack initiation and propagation for the P355NL1 pressure vessel steel. This model is combined with the generalized probabilistic fatigue model proposed by Correia aiming the generation of probabilistic fatigue crack initiation and propagation fields. In this study, the local stress and strains at the crack tip were obtained combining linear-elastic and elastoplastic analyses. The probabilistic fatigue crack growth rates fields for several stress R-ratios are estimated considering strain, SWT, and equivalent stress amplitude damage parameters. A comparison between the experimental FCG data and the generated probabilistic FCG fields is made with very satisfactory correlations being found.

Strengthening of RC Buildings with Steel Elements

Existing reinforced concrete (RC) buildings often need some strengthening interventions due to different reasons, such as change in usage, repair of visible damage or seismic strengthening. Nowadays, few guidelines and codes that specifically addressing this issue are available in Europe, even though a wide range of research activities and scientific literature is available. As a result, the lack of clarity and guidance from current codes leads most practitioners to rely on their engineering judgment and to resort to assessment procedures that are conceptually suitable to the design of new structures, rather than to the assessment of existing ones. Hence, this chapter aims at providing a brief discussion on the assessment procedures most commonly adopted by practitioners and at clarifying the adequacy of such approaches. Moreover, building on the manifold applications and versatility of steel, the use of steel elements in the strengthening of existing RC buildings is herein addressed. A number of strengthening techniques, from traditional to more innovative solutions, are presented alongside with a brief discussion on the relevant issues characterizing their design and performance.

Design and Assessment of Cold-Formed Steel Shear Wall Systems Located in Moderate-to-High Seismicity Regions

This paper presents a numerical simulation aimed at analysing the seismic performance of low- and mid-rise cold-formed steel (CFS) framed buildings, employing wood-sheathed shear wall panels (SWPs), designed according to a seismic design procedure compatible with the framework of the Eurocodes. To simulate their nonlinear behaviour, the structures were modelled adopting a recently developed deteriorating hysteresis model. In order to study the seismic performance and determine the seismic performance factors, Incremental Dynamic Analysis of 54 archetype buildings was performed in OpenSees. The seismic performance assessment was evaluated according to the methodology defined in FEMA P695. The results indicate that a behaviour factor q equal to 2 is appropriate for CFS framed structures using wood-sheathed SWPs lateral load resisting system designed for low and moderate seismicity regions. Further, the probabilistic seismic risk assessment of the studied frames, is presented. The importance and usefulness of the risk metrics are highlighted and adopted as an indicator to explore the behavioural features of the CFS-SWP structural system. Overall, the assessment procedure showed an acceptable seismic performance and therefore the CFS-SWP can be seen as a reliable structural solution to achieve performance-based objectives even in moderate-to-high seismicity regions.

Experimental Study and Numerical Assessment of the Flexural Behaviour of Square and Rectangular CFST Members under Monotonic and Cyclic Loading

This paper focuses on the characterization of the behaviour of Concrete Filled Steel Tubular (CFST) columns made with Rubberized Concrete (RuC), and on the development of an accurate numerical model for the simulation of CFST columns under monotonic and cyclic bending. The test campaign involves 18 CFST specimens with different configurations, namely the cross-section slenderness, the concrete strength, the axial load level and the lateral loading type. All CFST members tested exhibited good ductility under monotonic loading. The Eurocode 4 design provisions was verified against the test results and the design capacities of the CFST members were validated to be conservative. A comprehensive 3D Finite Element (FE) model was developed and calibrated based on test results. The FE model proved to be reliable in predicting the bending behaviour of CFST member, in terms of local buckling deformation modes, ultimate capacity and ductility of the CFST columns.

From Design to Earthquake Loss Assessment of Steel Moment-Resisting Frames

Steel moment-resisting frames (MRFs) are well known for their ductile and stable hysteretic behaviour. For this reason, they are an attractive and effective structural system for seismic resistance. Current seismic design codes, namely Eurocode 8, provide system performance factors that should be used in the seismic design under different ductility classes. However, recent research studies have shown that the use of the code-prescribed performance factors lead to stiffer and heavier structural solutions that are not consistent with the performance-based design assumptions. A new methodology, Improved Force-Based Design (IFBD), has recently been proposed with the aim of a more rational determination of the adopted value of the behaviour factor, q, instead of using the upper bound reference values provided by the design code. This paper investigates if the obtained values of q for both EC8 and IFBD concerning steel MRFs are not only adequate, but also provide sufficient margins against collapse under maximum considered earthquake (MCE) ground motions. To this end, the methodology proposed in FEMA P695 was used. Additionally, the expected direct economic seismic losses are computed according to the PEER-PBEE methodology.

Improved Seismic Design of Concentrically X-Braced Steel Frames to Eurocode 8

ABSTRACTSeismic design of concentrically X-braced steel frames to Eurocode 8 entails several difficulties to practitioners, often resulting in excessively heavy structural solutions. The main objec...