1,721,055 research outputs found
Performance-based structural fire design and testing of structures
No full textFire incident in buildings is common in Hong Kong and this could lead to heavy casualties due to its high population density, so the fire safety design of the framed structure is an important research topic. This paper describes a computer tool for determination of capacity of structural safety against various fire scenarios and the well-accepted second-order direct plastic analysis is adopted for simulation of material yielding and buckling. A computer method is developed to predict structural behaviour of bare steel framed structures at elevated temperatures but the work can be applied to structures made of other materials. These effects of thermal expansion and material degradation due to heating are required to be considered in order to capture the actual behavior of the structure under fire. Degradation of material strength with increasing temperature is included by a set of temperature-stress-strain curves according to BS5950 Part 8 mainly, which implicitly allows for creep deformation. Several numerical and experimental verifications of framed structures are presented and compared against solutions by other researchers. The proposed method allows us to adopt the truly performance-based structural fire analysis and design with significant saving in cost and time
Parameter Studies of Moving Force Identification in Laboratory
No full textThe parameters of both vehicle and bridge play an important role in moving force identification. This paper aims to investigate the effect of various parameters on Time Domain Method (TDM) and Frequency- Time Domain Method (FTDM). For this purpose, a steel bridge model and a vehicle model were constructed in laboratory. Bending moment and acceleration responses of the bridge were simultaneously measured when the model vehicle moved across the bridge at different speeds. The moving forces were identified using the TDM and FIDM and rebuilt responses were calculated from the identified forces for comparison of identification accuracy. Assessment results show that both the TOM and FTOM are effective field acceptable with higher accuracy but the TDM is better than the FTOM. Further work includes enhancement of the two methods and merging them into a Moving Force Identification System (MFIS)
Development of Simplified Method for Composite Bridge Design in Hong Kong
No full textThe Structures Design Manual for Highways and Railways (SDM) recommends that the composite bridges in Hong Kong shall be designed in accordance with the requirements of BS 5400: Part 5. The methods adopted in such analysis are usually highly analytical and computer based. On the other hand, simplified methods for composite bridge designs have been widely used overseas and yet such methods have not been applied very much in Hong Kong. The use of simplified methods will not only shorten the time spent on analysis, but will also permit the designer to retain a "feel" of behaviour of the bridge which is usually lost in traditional analyses. Previous reports have demonstrate its application to composite slab-on-girder bridges with two lanes in Hong Kong. This paper is aimed at developing a simplified method for composite bridges with more than two lanes. The proposed method has taken into account some aspects of a bridge that influence its load distribution. The proposed method is in a graphical form. Manual calculations employing formulae and charts are used to calculate the critical forces at internal and external girders. The results from the proposed method do not deviate significantly from those obtained by other rigorous bridge deck analyses. The calculated design forces for the girders could then be used for further steel design
Determination of Section Properties of Complicated Structural Members
No full textIn this paper, section properties, shear coefficient and torsional rigidity of complicated structural members with arbitrarily shape and multiply connected cross section is studied on the basis of theory of elasticity and finite element approach. With additional boundary conditions for the internal boundaries drawn from the continuous conditions of deformation and forces on the boundary, the torsion function and flexure function can be solved numerically from the second boundary-value problem. An improved definition of the shear coefficient is presented on the basis of the analysis of shear stresses distributed at the neutral axis of the cross section. An example is given to demonstrate the validity of the proposed computational approach. At last, the proposed approach is applied to determine the section properties of tower sections of tile Tsing Ma Bridge
Non-linear refined finite element elastic analysis of steel frames with generalized transverse member loads
No full textIn the finite element modelling of steel frames, external loads usually act along the members rather than at the nodes only. Conventionally, when a member is subjected to these transverse loads, they are converted to nodal forces which act at the ends of the elements into which the member is discretised by either lumping or consistent nodal load approaches. For a contemporary geometrically non-linear analysis in which the axial force in the member is large, accurate solutions are achieved by discretising the member into many elements, which can produce unfavourable consequences on the efficacy of the method for analysing large steel frames. Herein, a numerical technique to include the transverse loading in the non-linear stiffness formulation for a single element is proposed, and which is able to predict the structural responses of steel frames involving the effects of first-order member loads as well as the second-order coupling effect between the transverse load and the axial force in the member. This allows for a minimal discretisation of a frame for second-order analysis. For those conventional analyses which do include transverse member loading, prescribed stiffness matrices must be used for the plethora of specific loading patterns encountered. This paper shows, however, that the principle of superposition can be applied to the equilibrium condition, so that the form of the stiffness matrix remains unchanged with only the magnitude of the loading being needed to be changed in the stiffness formulation. This novelty allows for a very useful generalised stiffness formulation for a single higher-order element with arbitrary transverse loading patterns to be formulated. The results are verified using analytical stability function studies, as well as with numerical results reported by independent researchers on several simple structural frames
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Second-order elastic finite element analysis of steel structures using a single element per member
No full textFinite element frame analysis programs targeted for design office application necessitate algorithms which can deliver reliable numerical convergence in a practical timeframe with comparable degrees of accuracy, and a highly desirable attribute is the use of a single element per member to reduce computational storage, as well as data preparation and the interpretation of the results. To this end, a higher-order finite element method including geometric non-linearity is addressed in the paper for the analysis of elastic frames for which a single element is used to model each member. The geometric non-linearity in the structure is handled using an updated Lagrangian formulation, which takes the effects of the large translations and rotations that occur at the joints into consideration by accumulating their nodal coordinates. Rigid body movements are eliminated from the local member load-displacement relationship for which the total secant stiffness is formulated for evaluating the large member deformations of an element. The influences of the axial force on the member stiffness and the changes in the member chord length are taken into account using a modified bowing function which is formulated in the total secant stiffness relationship, for which the coupling of the axial strain and flexural bowing is included. The accuracy and efficiency of the technique is verified by comparisons with a number of plane and spatial structures, whose structural response has been reported in independent studies
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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