On the Insurmountable Size of Truss-like Structures

Galileo postulated the existence of an insurmountable size for stone columns bearing a useful load as the size for which the structure is only able to resist its self-weight. Herein a method for the determination of the unsurmountable size for truss-like structures is shown, given the form of these structures and the ratio between the allowable stress and the specific weight of the material (the material structural scope). Three types of bars are considered: straight bars, with solid and hollow rectangular cross-section, and catenary bars with circular cross-section —a limit and theoretical case for estimating a meaningful upper bound of the structural scope—. An approximate rule to estimate the structural efficiency —here named GA rule— is shown, and is compared with numerical solutions using the proposed method.

Launching the Vicario Viaduct: Andalucia, Spain

The Vicario Viaduct is located in the A-44 motorway, in the South-East part of Spain. It crosses a natural gorge, near the town of Ízbor in the province of Granada. A single continuous steel concrete composite deck, 24 m wide and 175 m long, divided in two 87,5 m spans, has been built. The cross section is a single structural steel box, 8,00 m wide and 4,52 m deep. The total width of 24 m is reached adding a strut and tie system each 4,375 m on both sides of the box. The steel parts of the deck were entirely constructed in the workshop and then they were erected on site just behind one of the abutments. Finally a 27.5 m long steel nose was connected to launch the deck. The main problems have been the curved shape of the deck (1420 m radius in plan) producing a non symmetric transverse distribution of reactions on each support and the cantilever reaching 87,5 m long, producing a maximum deflection of 1500 mm

Use of subpixel techniques in pocket cameras to measure vibrations and displacements

Presentación oral SPIE Photonics Europe, Brussels, 16-19 April 2012.

Hormigón Armado y Pretensado. Presentaciones (curso 2011-2012)

Presentaciones de los temas que integran los contenidos de la asignatura "Hormigón Armado y Pretensado", impartida en las titulaciones de Ingeniería Técnica de Obras Públicas, Ingeniería Geológica y Grado en Ing. Civil.

Steel Pedestrian Bridge to Protect a Unique Tree

This paper describes the “Variation Guggenheim 3: Mirador de la palmera” project, situated in Daya Vieja (Alicante-Spain). This structure is inspired by the Guggenheim museum of New York and is designed to protect a land-mark palm-tree from wind loads. This six – trunk palm tree was declared monument by the Valencian government in 2012. The structure that now protect it appears to fly around de palm tree creating a helicoidally skywalk made of steel, while retrofitting the lateral trunks of the tree to protect them from collapse. An 18 m. long straight beam starts on the top of this helix, and stretches towards a lookout point that offers a view of the whole village and its surroundings. The reduction of the visual impact of the structure on the tree was a major aim for the project design. The structural elements are as slender as possible to avoid the visual obstruction of tree. They are painted white, while the walkway steel corrugated plate is painted green in order to highlight its neat shape among the blur created by the apparent mess of bars of the supporting structure. The two main piles of this pedestrian bridge were designed in steel and geometrically resemble trees. A Ground Penetrating Radar analysis was performed to detect the palm root location and to decide the best foundation system. Slender cast in-situ steel-concrete micropiles along with a concrete pile-cap, raised some centimeters above the ground level, were used to reduce the damage to the roots. The projected pile-cap is a slender, continuous, circular ring; which geometry resembles a concrete bench. This structure has been a finalist in the Architecture Awards for the 2010-2014 best construction projects, held by the Diputación de Alicante.

A Unique Prestressed Concrete Pedestrian Bridge in Spain

This paper describes the so-called Kiss Bridge. This structure resembles a kiss, a subtle touch of structures. The beams have been structurally designed to adapt the Japanese art of paper folding called "origami." The material used for constructing the floating beams is white reinforced concrete in the form of folded shells. The two geometrically different parts have distinct structural behaviors. The length of the main pathway of both structures is over 60 m. The pedestrian bridge crosses an artificial rainwater channel with a skew of 45° with respect to the referred channel. The joint between the cantilever structure and the Y-shaped one is located over the middle of the channel. Each stretch has different transversal sections. The pedestrian bridge is made with prestressed self-compacting reinforced concrete of 60 MPa. The foundation is shallow, comprising footings and footing beams made of 25 MPa conventional concrete. The cantilever structure with its foundations is designed as a semi-integral bridge whereas the Y-shaped one is an integral structure. The dynamic behavior of the structure was carefully studied to ensure that the dynamic loads generated by pedestrians do not cause excessive vibrations, especially to the cantilever structure, which could present dynamic interactions with the pedestrians walking. The bridge was recognized, in the 2014 edition of the fib Awards for Outstanding Concrete Structures, for having made a valuable contribution to the image and promotion of concrete structures.

Modéle qui offre la restauration du Colisée de Rome tel qu'il était originairement : de la soixantième partie de la réalité mesure linéaire /

Mode of access: Internet.

Extending the service life of existing bridges by increasing their load carrying capacity /

Mode of access: Internet.

Methods to reduce built-in residual stresses in steel bridge diaphragms (Phase I) /

"July 2000."

ViewPoint /

Title from cover.

Averting surprises in the Pacific Northwest /

Mode of access: Internet.

Analysis of statically indeterminate structures.

Mode of access: Internet.

Drying of porous building materials: hydraulic diffusivity and front propagation

One-dimensional drying of a porous building material is modelled as a nonlinear diffusion process. The most difficult case of strong surface drying when an internal drying front is created is treated in particular. Simple analytical formulae for the drying front and moisture profiles during second stage drying are obtained when the hydraulic diffusivity is known. The analysis demonstrates the origin of the constant drying front speed observed elsewhere experimentally. Application of the formulae is illustrated for an exponential diffusivity and applied to the drying of a fired clay brick.

Analysis of the thermal stress behaviour of functionally graded hollow circular cylinders

This paper presents an analysis of the thermomechanical behavior of hollow circular cylinders of functionally graded material (FGM). The solutions are obtained by a novel limiting process that employs the solutions of homogeneous hollow circular cylinders, with no recourse to the basic theory or the equations of non-homogeneous thermoclasticity. Several numerical cases are studied, and conclusions are drawn regarding the general properties of thermal stresses in the FGM cylinder. We conclude that thermal stresses necessarily occur in the FGM cylinder, except in the trivial case of zero temperature. While heat resistance may be improved by sagaciously designing the material composition, careful attention must be paid to the fact that thermal stresses in the FGM cylinder are governed by more factors than are its homogeneous counterparts. The results that are presented here will serve as benchmarks for future related work. (C) 2003 Elsevier Science Ltd. All rights reserved.

Analysis of the free vibration of rectangular plates with central cut-outs using the discrete Ritz method

We present an analysis of the free vibration of plates with internal discontinuities due to central cut-outs. A numerical formulation for a basic L-shaped element which is divided into appropriate sub-domains that are dependent upon the location of the cut-out is used as the basic building element. Trial functions formed to satisfy certain boundary conditions are employed to define the transverse deflection of each sub-domain. Mathematical treatments in terms of the continuities in displacement, slope, moment, and higher derivatives between the adjacent sub-domains are enforced at the interconnecting edges. The energy functional results, from the proper assembly of the coupled strain and kinetic energy contributions of each sub-domain, are minimized via the Ritz procedure to extract the vibration frequencies and. mode shapes of the plates. The procedures are demonstrated by considering plates with central cut-outs that are subjected to two types of boundary conditions. (C) 2003 Elsevier Ltd. All rights reserved.