Search results for "Concrete."
showing 10 items of 249 documents
Getting into the groove: Opportunities to enhance the ecological value of hard coastal infrastructure using fine-scale surface textures
2015
Concrete flood defences, erosion control structures, port and harbour facilities, and renewable energy infrastructure are increasingly being built in the world’s coastal regions. There is, however, strong evidence to suggest that these structures are poor surrogates for natural rocky shores, often supporting assemblages with lower species abundance and diversity. Ecological engineering opportunities to enhance structures for biodiversity conservation (and other management goals) are therefore being sought, but the majority of work so far has concentrated on structural design features at the centimetre–meter scale.\ud \ud We deployed concrete tiles with four easily-reproducible fine-scale (m…
Frictional effects in structural behavior of no-end-connected steel-jacketed RC columns: Experimental results and new approaches to model numerical a…
2017
Steel jacketing of reinforced concrete (RC) columns is a common retrofitting technique used to restore bearing and deformation capacity of buildings presenting structural deficiencies. For practical reasons, steel angles are in several cases arranged leaving a gap with the end beams or slabs. Despite this disconnection, the angles are still able to support a non-negligible portion of load because of the frictional forces developed along the column-angle contact interface. In these cases, the definition of computational numerical and analytical models for the assessment of reinforced cross sections becomes more complex and must be handled with care. The actual load-carrying capacity of the a…
Fundamental period of infilled reinforced concrete frame structures
2016
AbstractThe fundamental period of vibration appears to be one of the most critical parameters for the seismic design and assessment of structures. In the present paper, the results of a large-scale analytical investigation on the parameters that affect the fundamental period of reinforced concrete structures are presented. The influence of the number of storeys, the number of spans, the span length, the infill wall panel stiffness and the percentage of openings within the infill panel on the fundamental period of infilled RC frames was investigated. Based on these results, a regression analysis is applied in order to propose a new empirical equation for the estimation of the fundamental per…
Failure by corrosion in PC bridges: A case history of a viaduct in Italy
2016
Purpose The paper illustrates a viaduct collapse due to corrosion phenomena. Moreover, a contribution to the issues related to both the control of existing structures and design methods to be followed for the construction of new buildings is provided. Design/methodology/approach The objectives were achieved by in situ observations and numerical analyses. The effects of corrosion phenomena are investigated, and the progressive collapse analysis is provided to be helpful in this case. Findings The damages induced by corrosion phenomena have caused the collapse of the viaduct taken in to account. The performed numerical analyses were able to reproduce the effects of corrosion in terms of redu…
Incremental dynamic based fragility assessment of reinforced concrete structures: Stationary vs. non-stationary artificial ground motions
2017
Abstract Artificial and natural records are commonly employed by researches and practitioners to perform refined seismic assessments of structures. The techniques for the generation of artificial records and their effectiveness in producing signals which are significantly representative of real earthquakes are still debated as well as results of the consequent seismic assessment to expect from their application. The paper presents an in-depth comparative study highlighting the effect of employing different typologies of artificial ground motion records on seismic assessment results, especially addressing seismic fragility curves. Three sets of 50 stationary, nonstationary evenly modulated a…
Analytical model for high-strength concrete columns with square cross-section
2008
In the present paper a mechanical model to predict the compressive response of high strength short concrete columns with square cross-section confined by transverse steel is presented. The model allows one to estimate the equivalent confinement pressures exercised by transverse steel during the loading process taking into account of the interaction of the stirrups with the inner core both in the plane of the stirrups and in the space between two successive stirrups. The lateral pressure distributions at hoop levels are obtained by using a simple model of elastic beam on elastic medium simulating the interaction between stirrups and concrete core, including yielding of steel stirrups and dam…
Strengthening of steel-reinforced concrete structural elements by externally bonded FRP sheets and evaluation of their load carrying capacity
2014
Abstract The paper proposes a preliminary design tool for reinforced concrete (RC) elements strengthened by fiber-reinforced-polymer (FRP) sheets to be used in civil engineering applications and in particular in medical buildings. The design strategy is based on limit analysis theory and utilizes a numerical procedure which provides a direct method to determine peak load, failure mode and critical zones of the structural elements of interest.
Serviceability of segmental concrete arch-frame bridges built by cantilevering
2013
The evaluation of the safety degree in service life for a segmental prestressed concrete bridge built by the cantilever method presents different aspects related to strength, deformability, durability and to effects of time-dependent phenomena as creep and shrinkage. The case-study of a prestressed concrete frame bridge with inclined piers is presented, built by cantilevering, with precast segments. By considering the fundamental items of design and construction stages, the implications due to the arch effect in this static scheme are investigated, with respect to an equivalent bridge with a final scheme of continuous girder on vertical piers. The birth of a significant value of axial force…
Seismic Performance of Masonry Infilled RC Structures via N2 Pushover Assessment Procedures: Outcomes under Different Modeling Hypotheses of a Case S…
2016
The assessment of the capacity of RC masonry infilled RC structures constitutes nowadays a still debated issue. Pushover based procedures for the evaluation of seismic performance, such as N2 method, are largely used in practice and in force in several technical codes. The latter has proved to be reliable for a large number of structural typologies, however in the case of infilled frames, the choices made on the modelling strategy may radically modify the outcomes observable from the capacity curves and the consequent performance levels achievable. In the paper, the extent of different modelling choices on the results of the application of N2 procedure is investigated by the deep analysis o…
Shear strength of High-strength concrete beams: modeling and design recommendations
2014
Abstract In the present paper, the flexural and the shear resistance of high strength reinforced concrete (HSC) beams with longitudinal bars, in the presence of transverse stirrups is analyzed both theoretically and experimentally. The experimental researches here presented are parts of previous researches carried out by the author. Researches refer to HSC beams with high percentages of steel bars failing in shear and in flexure. From the analytical point of view, a model based on the evaluation of the resistance contribution due to beam and arch actions including bond splitting and concrete crushing failure modes is developed and presented. The model was verified against available experime…