Structural optimisation is a topic which gathers the interest of many research teams and engineers. Its purpose is to minimise an objective function, such as the weight of a structure, subjected to certain constraints (e.g. compliance of structural members with code requirements). In this paper, optimal design (in terms of shape and sizing) of through-truss steel bridges is performed. Several cases of simply supported bridges with different spans (40m, 50m and 60m) and varying width, corresponding to one or two traffic lanes, were examined. For the aforementioned bridges, the effect of three deck types (reinforced concrete deck, fiber reinforced polymer deck and steel deck) on the weight of the truss and the total weight was investigated. Least-weight shape and sizing optimal design was executed, with the height of the truss and the cross-section areas of its members constituting the design variables of the problem. The structural analysis and design were conducted in accordance with the specifications of the Eurocodes. The influence of both the height-to-span ratio and the deck type on the weight of the truss, the total weight and the cost is discussed based on the results obtained from the optimisation procedure.
The New Faliron steam-electric station, the first one in Greece, is a listed historical building. The initial structure was constructed at the start of the 20 th century but a number of interventions followed until the 1960s. The structure was built with natural stone masonry, steel trusses and floors (with jack arches and joist fillers) and concrete floors reinforced with twisted cold formed rebars. The 12.5m high masonries practically lack any lateral restraints while large openings (doors, windows) exist. This paper presents brief information on the history of the structure, phases of construction, description of structure (dimensions, types of structural systems, etc), material properties and pathology. In addition, detailed information is presented regarding the assessment performed in accordance with the current code specifications (Eurocodes), including seismic actions. Especially for the masonry, a detailed finite element model was developed, whereas the seismic forces were evaluated through alternative methodologies (modal response spectrum analysis per EC8 and time history analyses). For the assessment of the RC part a displacement based methodology was applied as it is restrained by the surrounding masonry walls. From the assessment analysis, useful conclusions are drawn regarding the seismic performance of high masonry structures without lateral restraints and the behaviour of similar industrial structures under seismic effects.
The main objective of the present study is the assessment and retrofit of an existing reinforced concrete building. In particular, the study concerns the municipal theater of the city of Volos, Greece and it was carried out following the provisions and requirements of the Greek Retrofitting Code (KAN.EPE.), which adopts the Performance Based Design (PBD) concept. The theater was built during the 70s and was designed according to the Greek Royal Decrees of 1954 and 1959. The theater consists of the stage and the auditorium, which were analyzed independently, because they constitute two disjoint reinforced concrete (RC) structures. Their structural system consists of spatial frames and shear walls. The columns and the beams are simulated with beam elements with concentrated plasticity and the shear walls with equivalent diagonal truss elements which simulate the shear behavior of the wall structural element. Nonlinear static (Pushover) analysis is applied in order to estimate the seismic performance of the two structures for two performance objectives (A2 and B1 according to the provisions of KAN.EPE.). These correspond to the "Operational" and "Life Safety" performance levels for seismic hazard levels with a 50% and 10% probability of exceedance in 50 years, respectively. A retrofitting scenario is proposed for both the stage and the auditorium in order for the performance objectives to be met. It includes concrete jacketing of certain beams, columns and shear walls as well as strengthening of specific beams with fiber-reinforced polymers (FRPs).
The main objective of the present study is the assessment and retrofit of an existing road bridge that is located in Cyprus over the river Kouris. In particular the study concerns in a road bridge with seven spans of 10.5 m + 5 * 12.6 m + 10.5 m, a cross section width of 7.10 m and a 5 m piers height that was constructed in the early 50's. The structural system of the bridge comprises of cast in situ reinforced concrete T-beams and slab deck that is simply supported on masonry piers. According to the new urban plan to design the bridge should now accommodate two lanes per direction, a pedestrian walkway and a cycling lane with total cross section width of new deck 15.60 m. The deck of the bridge widened using for aesthetic reasons the same cross section type and the new T-Beams and slab deck connected monolithically to the existing one. The existing part of the deck was strengthened with reinforced concrete jacketing due to inadequacy in shear resistance. Major challenge of the project posed the existing masonry pier layout that was insufficient to carry the new design seismic forces. New piers, founded on piles, were designed adjacent to the existing piers in order to support the new widened part of the bridge, and also to bear all the horizontal loads arising from the masses of the total deck. Sliding bearings (free movement) placed in the part of the bridge over the existing piers and elastomeric bearings with movement only in the longitudinal direction placed in the new piers.
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