Periodic truss materials (PTM) -or Lattice Block Materials (LBM) -belong to the family of the so called ultralight cellular materials, which have attractive engineering properties such as high stiffness/weight ratio and high energy absorption capability. These materials are obtained by the periodic repetition of a unit cell given by a truss structure, so that the orientation of the bars and the cross sectional areas define the material9s macroscopic behavior. In recent years, the development of new process technologies for manufacturing PTMs have brought increased interest in modeling their structural and thermal behavior. In addition to usual analytical and numerical approaches for analyzing the effect of different unit cell configurations on macroscopic properties, optimization techniques have been applied in order to tailor unit cells for achieving desired macroscopic constitutive properties. The present contribution uses mathematical programming for tailoring PTMs through a number of optimization problems in which selected homogenized elastic or thermal constitutive properties are maximized, at the same time that isotropy tries to be enforced by the inclusion of adequate material symmetry constraints. Cross sectional areas and nodal coordinates of the bars are adopted as design variables. 2D examples are presented showing qualitative agreement with results available for 2D elasticity.

In recent years, much attention has been directed to the study of ultralight periodic cellular materials, such as the so called Periodic Truss Materials (PTMs), which are made up of truss-like unit cells. Application of these materials has its best potential in structures subjected to multifunctional, and sometimes conflicting, engineering requirements. Hence, optimization techniques can be employed to help finding the shape of the optimal unit cell for a given multifunctional application. Although the result can be geometrically complex, this difficulty can be minored in view of modern additive manufacturing technologies. This work presents a parameter/ topology optimization procedure to design the particular unit cell geometry (that is, finding the cross sections of the bars) that results in a macroscopic material with optimum homogenized elastic or/and thermal constitutive properties. Emphasis is devoted to analyze the effect of enforcing independently elastic or thermal isotropy in the macroscopic material behavior. Although isotropic behavior can be imposed through adequate cell symmetries, an equivalent effect can be achieved by satisfying equality constraints relating constitutive coefficients. A sequential quadratic programming algorithm (SQP) is adopted, thus enforcing equality constraints gradually and within a tolerance range. This results in an enlarged search space at intermediate stages, rendering an effective strategy to solve the optimization problem. Different 3D cases with engineering appeal are solved and the results discussed.

<p>The Canot Bridge is a triple arch bridge, rebuilt in 1949, after WWII. It is located in the center of the city of Besançon, over the Doubs River. The span of each of the three main arches is 27,40 m and the rise is 4,31 m. In the cross section, the structure consists in 3 arches, having a width of 2,20 m and a height varying from 0,80 at the crown to 1,00 m at the spring. The particular point is that the arches are made of concrete with no reinforcement. The deck is supported by the arches by means of diaphragms. Initially, the bridge was supporting one lane in each direction. In 1979, the bridge was widened with an additional concrete cantilever structure, allowing two lanes in each direction. Two lanes will be sacrificed to allow the bridge to carry 2 tramway lines.</p><p>The object of the study was to check the structure under these new load cases. One of the issues is that neither any information about the building phases nor the bearing conditions of the arches on the piers was available for the study. This article will present the results and the strengthening works that were decided. Works on site have started in August 2012 and will last until April 2013.</p>

<p>Arcadis recently designed and completed two complex bridges using the concept of composite plates (see EN 1994-2, section 9). The first bridge using this method, the Saint Lazare Bridge, crosses the busiest railway network in the city of Paris. The bridge consists of a 125 m long steel box deck with a deck width of 17,5 m resting on V-shaped piers. The thickness of the concrete slab is 120 mm. The second bridge, currently under construction, is the viaduct of Guerville. This viaduct is a 360 m long concrete-steel composite bridge with two I-shaped girders linked together by floor beams. The design of the central part of the deck, which is governed by the central span length of 116,5 m, required a lighter and thinner slab than the typical reinforced concrete top slab. This led to the use of a composite plate, 160 mm thick for the 157 m central part of the bridge. This paper presents the general design of both bridges along with the specific methodologies and calculations used for the composite deck plate designs.</p>

<p>The Eurométropole de Strasbourg (EMS) has awarded the Strasbourg Public Transport Company (CTS) the project to extend Line D of the tram to Kehl (Germany); work started in 2014. The project extends the Strasbourg network into Germany and will be key to developing cross-border links.</p><p>Its completion requires building some spectacular infrastructures, including the Rhine Bridge. Selected by the EMS and the town of Kehl on the recommendation of the CTS, the project's contracting agent, the design and build of the structure was awarded to a consortium of businesses comprising Bouygues TPRF, Victor Buyck SC, Lingenheld TP, Früh Ingenieurbau(*), Arcadis and Marc Barani Architects.</p>