Search results for "Diagonal"
showing 10 items of 124 documents
Finite linear spaces in which any n-gon is euclidean
1986
Abstract An n-gon of a linear space is a set S of n points no three of which are collinear. By a diagonal point of S we mean a point p off S with the property that at least two lines through p intersect S in two points. The number of diagonal points is called the type of S. For example, a 4-gon has at most three diagonal points. We call an n-gon euclidean if (roughly speaking) it contains the maximal possible number of 4-gons of type 3. In this paper, we characterize all finite linear spaces in which, for a fixed number n ⩾ 5, any n-gon is euclidean. It turns out that these structures are essentially projective spaces or punctured projective spaces.
Analytical evaluation of steel–concrete composite trussed beam shear capacity
2015
A calculation method for the prediction of the shear resistance of precast composite beams, named Hybrid Steel Trussed-Concrete Beams (HSTCBs), is herein proposed. HSTCBs are constituted by a prefabricated steel truss embedded within a concrete matrix cast in situ so that, after curing, the two materials work together in the mechanical response of the composite structural element, the steel truss behaving as reinforcement of the beam. The proposed analytical model is developed on the basis of the results of a reference experimental campaign of three-point bending tests available in the literature, carried out on specimens of HSTCB designed in order to attain a shear failure. Furthermore, th…
Evaluation of infilled frames: an updated in-plane-stiffness macro-model considering the effects of vertical loads
2015
The influence of masonry infills on the in-plane behaviour of RC framed structures is a central topic in the seismic evaluation and retrofitting of existing buildings. Many models in the literature use an equivalent strut member in order to represent the infill but, among the parameters influencing the equivalent strut behaviour, the effect of vertical loads acting on the frames is recognized but not quantified. Nevertheless a vertical load causes a non-negligible variation in the in-plane behaviour of infilled frames by influencing the effective volume of the infill. This results in a change in the stiffness and strength of the system. This paper presents an equivalent diagonal pin-jointed…
U.I.R.D.A. – Unbuilt Italian Rationalism Digital Archive
2018
For twenty years, the architecture of Italian rationalism through the digital modelling has been investigated. Very often, the production of a model and the consequent representation of tridimensional views, in many case studies, as outcome of the research on architecture have been considered. Actually, the digital model, intended as a critical tool, has to be conceived as a ‘starting point' for graphic analysis of architecture and not as the outcome. Indeed, it is associated to other graphics, sometimes not ‘deducted' from the model, useful for the understanding/translation of architecture. The construction of the model is not the construction of a simple image, operation, which is often c…
Elementary presentation of self‐consistent intermediate Hamiltonians and proposal of two totally dressed singles and doubles configuration interactio…
1994
Intermediate Hamiltonians are effective Hamiltonians which are defined on an N‐dimensional model space but which only provide n<N exact eigenvalues and the projections of the corresponding eigenvectors onto the model space. For a single root research, the intermediate Hamiltonian may be obtained from the restriction of the Hamiltonian to the model space by an appropriate, uniquely defined dressing of the diagonal energies or of the first column. Approximate self‐consistent dressings may be proposed. The simplest perturbative form gives the same result as the original 2nd order intermediate Hamiltonian or the ‘‘shifted Bk’’ technique but it is of easier implementation. Self‐consistent inclus…
Spin Chains with Non-Diagonal Boundaries and Trigonometric SOS Model with Reflecting End
2011
In this paper we consider two a priori very different problems: construction of the eigenstates of the spin chains with non parallel boundary magnetic fields and computation of the partition function for the trigonometric solid-on-solid (SOS) model with one reflecting end and domain wall boundary conditions. We show that these two problems are related through a gauge transformation (so-called vertex-face transformation) and can be solved using the same dynamical reflection algebras.
Infilled frames: Developments in the evaluation of cyclic behaviour under lateral loads
2005
In order to consider the modified seismic response of framed structures in the presence of masonry infills, proper models have to be formulated. Because of the complexity of the problem, a careful definition of an equivalent diagonal pin-jointed strut, able to represent the horizontal force-interstorey displacement cyclic law of the actual infill, may be a solution. In this connection the present paper, continuing a previous work in which a generalised criterion for the determination of the ideal cross-section of the equivalent strut was formulated, analizes some models known in literature for the prediction of the lateral cyclic behaviour discussing their field of validity. As a support of…
A branch and bound algorithm for the matrix bandwidth minimization
2008
In this article, we first review previous exact approaches as well as theoretical contributions for the problem of reducing the bandwidth of a matrix. This problem consists of finding a permutation of the rows and columns of a given matrix which keeps the non-zero elements in a band that is as close as possible to the main diagonal. This NP-complete problem can also be formulated as a labeling of vertices on a graph, where edges are the non-zero elements of the corresponding symmetrical matrix. We propose a new branch and bound algorithm and new expressions for known lower bounds for this problem. Empirical results with a collection of previously reported instances indicate that the propose…
Normalizing biproportional methods
2002
International audience; Biproportional methods are used to update matrices: the projection of a matrix Z to give it the column and row sums of another matrix is R Z S, where R and S are diagonal and secure the constraints of the problem (R and S have no signification at all because they are not identified). However, normalizing R or S generates important mathematical difficulties: it amounts to put constraints on Lagrange multipliers, non negativity (and so the existence of the solution) is not guaranteed at equilibrium or along the path to equilibrium.
Influence of column shear failure on pushover based assessment of masonry infilled reinforced concrete framed structures: A case study
2017
Structural frames, constructed either of steel or reinforced concrete (RC), are often infilled with masonry panels. However, during the analysis of the structural frames, it has become common practice to disregard the existence of infills because of the complexity in modeling. This omission should not be allowed because the two contributions (of infills and of frames) complement each other in providing a so different structural system. The use of different modeling assumptions significantly affects the capacity as well as the inelastic demand and safety assessment. In specific, the adoption of equivalent diagonal pin-jointed struts leaves open the problem of the evaluation of the additional…