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<p> Chilina Bridge is a 562 long prestressed concrete viaduct with two 11.3 m wide decks in the city of Arequipa (Peru) with span scheme: 100+157+142+102+61 m. Free Cantilever Method construction is used. High seismicity in the area reaches Peak Ground Acceleration of 0.6 g and involves special analysis and detailing. The new bridge will become the largest urban bridge in Peru when completed. Construction started in March 2013 and will be finished by the end of 2014.</p><p> Seismic analysis is done according to AASHTO specifications for a 1000 year return period Earthquake. Seismic displacement demands are as high as 90 cm and 45 cm in transverse and longitudinal direction.</p>

Structural engineers usually make simple hand calculations to pre-design structures before performing further complex analysis. However, in the case of structures subjected to impact loads, the problem is quite difficult to cope with, due to the lack of knowledge about simplified methods of analysis that can reproduce with sufficient accuracy the structural behavior, in order to establish an adequate pre-dimensioning, prior to a computer calculation. In this paper, a new formulation is presented to solve the problem of large mass impact on any kind of structure in a simplified way. The method enables a force equivalent to the impact load to be obtained that enables analysis as a static load case.

<p>The High Speed Railway (HSR) link Madrid - Extremadura crosses over River Almonte with a great arch viaduct of high - performance concrete. The main span of this structure is 384 meters.</p><p>This paper explains the exceptional techniques and structural analysis outside the usual engineering work that have been developed to reach its design and construction. These studies include the selection of the antifunicular arch axis taking into account construction process and train loads, geometric and material nonlinear analysis, dynamic analysis and aerolastic behaviour.</p>

<p> The Almonte River arch bridge over the Alcántara Reservoir, which is part of the Madrid- Portuguese Border High Speed Rail (HSR) link, is a challenge for bridge design, engineering and construction. Its 384-m main span will make this major project become the largest HSR arch in the world and the largest railway bridge in Spain. With the aim of giving response from the design stage to the specific problems of a HSR crossing with large span and length, a formally and structurally innovative design has been used: the arch, linked to the deck at the crown, has an octagonal section with variable depth and width in its central 210 m, from where it splits itself into two legs with irregular hexagonal section until its springings. The design joins together structural efficiency, out-of-plane stability (as HSR horizontal deflection limits require), improved response to wind loads (as exhaustive wind tunnel tests have proved), transparency, aesthetics and durability.</p>