Search results for "construct"

Timber anti-seismic devices in historical architecture in the Mediterranean area

2017

Questo lavoro esamina l’uso di un dispositivo strutturale in legno storico utilizzato come rinforzo della muratura per i sistemi di prevenzione sismica nell'area mediterranea. Tale tecnologia viene realizzata mediante un telaio tridimensionale tridimensionale di legno incorporato nella muratura di pietra per legare insieme le varie parti strutturali e contribuire alla resistenza sismica complessiva. Molto spesso, questo principio costruttivo fu esteso non solo per le parti più deboli, ma per l'intero edificio, creando nuove configurazioni strutturali che erano in grado di assorbire gli effetti delle azioni sismiche. Dalle esperienze costruttive di epoca romana (opus craticium), questo siste…

Theoretical approaches for modelling buckling effects in rebars of RC members

2017

Buckling of longitudinal bars in reinforced concrete (RC) members is definitely a critical issue in framed structures subjected to seismic loads. Second order effects can affect the compressive stress–strain law of steel bars, influencing ductility calculations of RC structures. Moreover, literature studies show that buckling can occur over a length wider than stirrups’ pitch (global buckling mode), involving more stirrups and inducing large deflections in the bar. If the critical length is not carefully estimated, stirrups’ failure can occur, causing also the sudden loss of confining effects in concrete. This paper presents the results of different approaches for calculating the crit…

Effects of corrosion on a steel bowstring bridge in marine environment: A case-study of assessment and retrofit

2021

The case-study of a steel bowstring bridge set in a marine environment and highly damaged by corrosion is presented. The bridge was built in 2004 and was repainted for corrosion protection in 2010. Despite the recent construction and the maintenance interventions, many structural elements like hangers are highly damaged by corrosion with decreasing performance in terms of serviceability and ultimate limit states. A deep investigation was carried out in order to assess the bridge and to establish the necessary retrofit actions to be carried out in the near future. In-situ tests reveal the reduced performance of the original steel in terms of strength and corrosion protection, together with t…

Steel and composite tied-arch bridges: a conceptual approach to structural design

2021

The behaviour of tied-arch bridges with composite decks (bowstring bridges) is overly sensitive to the different choices made by the designer in the first phases of the conceptual approach, mainly in the design of the arch and the deck. The geometry of the arch shape, the design of the arch–tie joint and the construction sequence can significantly modify the global behaviour in terms of stress state and deformed configuration. After a general discussion on the different parameters affecting the behaviour of bowstring bridges with steel–concrete composite decks, the consequences of choices made in the conceptual design phases are discussed, analysing the effects of each choice on the global…

Simplified Procedure for Evaluating the Effects of Creep and Shrinkage on Prestressed Concrete Girder Bridges and the Application of European and Nor…

2013

The effects of time-dependent phenomena on concrete prestressed girder bridges are investigated. The study concerns the case of bridges built directly in their final configuration and that of bridges built by a sequence of stages in which geometry, restraints, and loads vary until the final configuration is achieved. An analytical approach based on the principles of aging linear viscoelasticity and the age-adjusted effective modulus method is followed. The paper has two aims: the first is to provide an efficient and simplified tool for the evaluation of the structural response in the early stages of design; the second is to compare the results of the analyses on actual cases of bridges when…

Green Industrial Analysis

2012

RC column externally strengthened with RC jackets

2013

In this paper the behaviour in compression of RC columns externally strengthened with concrete jacketing is analysed and a cross-section analysis of the jacketed member under axial load and bending moment is developed. The focus was to study the effect of confinement of concrete jacket on concrete core and the behaviour of compressed bars with buckling effects. Some other important aspects such as shrinkage, creep, old to new concrete surfaces and bond split effects were not included in the model because: the use of thick non-shrink grout jacket and a well-roughened surface of old-to-new concrete was supposed; long term effects were included though corrective coefficients for monolithic beh…

Effect of FRP Wraps on the Compressive Behaviour of Slender Masonry Columns

2017

In the last decade, Fibre Reinforced Polymer (FRP) wrapping technique has become a common method to retrofit masonry piers or columns with poor structural performances. The passive confinement effect induced by the external wrap allows increasing the compressive strength and ductility of the member. Several studies highlighted as the efficacy of this technique is affected by several key parameters, including the shape of the transverse cross section, stress intensification at the strength corner of sharp sections, amount and mechanical properties of adopted composite. Despite this technique has been widely studied from both theoretical and experimental point of view, most of studies focused…

Experimental performance evaluation of a vapour compression refrigerating plant when replacing R22 with alternative refrigerants

2011

Abstract This paper presents the results of an experimental analysis comparing the performance of a vapour compression refrigerating unit operating with R22, and its performance in comparison to a new HFC fluid, substituting the former according to Regulation No 2037/2000. In particular, the plant working efficiency was first tested with R22 and then with three new HFC fluids: R417A, R422A and R422D. The investigation verified that despite the case of substitution and the advantage of being able to continue to use mineral oil as a lubricant in the compressor, the performance with the new tested fluids did not result as efficient as when using R22.

A measurement methodology for monitoring a CHCP pilot plant for an office building

2003

Abstract In Mediterranean areas, climate conditions determine quite equal demand both for thermal and cooling energy. The possibility to convert a cooling demand in thermal one through an absorption chiller allows to extend widely the number of running hours of a cogeneration plant. A trigeneration pilot plant for two office building is described, in which an integrated lay-out includes a NG prime mover with heat exchanger, an absorption chiller and a reversible heat pump. The pilot plant is completed and pre-running test were performed. Different fluid dynamics parameters will be monitored, in order to build the actual cumulative curve for thermal power. The measurement methodology is also…