Papers
Info
The effect of skew angle on the mechanical behaviour of masonry arches
tThis paper presents the development of a three dimensional computational model, based on the DiscreteElement Method (DEM), which was used to investigate the effect of the angle of skew on the load carryingcapacity of twenty-eight different in geometry single span stone masonry arches. Each stone of the archwas represented as a distinct block. Mortar joints were modelled as zero thickness interfaces which canopen and close depending on the magnitude and direction of the stresses applied to them. The variablesinvestigated were the arch span, the span: rise ratio and the skew angle. At each arch, a full width verticalline load was applied incrementally to the extrados at quarter span until collapse. At each load increment,the crack development and vertical deflection profile was recorded. The results compared with similar
Year: 2014
Number Pages:
53-59pp.
Author(s): Sarhosis, V.; Oliveira, D.; Lemos, J. V.; Lourenço, P.
: Mechanics Research Communications
Editor: Elsevier
Volume:
61.
Keywords: Discrete elements; Numerical modelling; Arches; Masonry
Info
The evaluation of uncertainty in mass calibration: Possible approaches in a comparison study
N/A
Year: 2014
Number Pages:
7pp.
Author(s): Sousa, J.; Forbes, A. B.; Ribeiro, A.; Harris, P. M.; Carvalho, F.; Bacelar, L.
: Journal of Physics
Volume:
Conference Series 459 (2013) 012033.
Info
The evaluation of zinc hydroxychloride cement pastes for the conservation of damaged tiles
This study examines the potential of zinc hydroxychloride cement pastes as a fill material for the conservation of damaged historic tiles. The scope for modifying various properties was investigated by the preparation of numerous versions of the basic formulation in which the ratio of the three principal constituents zinc oxide powder, an aqueous solution of zinc chloride, and a mineral aggregate was varied. The importance of adjusting these variables for optimal performance was confirmed. The concentration of the zinc chloride solution was also found to be an important factor as this affected the useful working time before cementation occurred. The resultant reaction products were examined by x-ray diffraction in several cases. Compressive and flexural strength tests were undertaken on a number of the variants and on a commercial formulation (Lithos Arte). Observations of the cement-tile interface (using optical and scanning electron microscopy) were made. In addition, adhesion was assessed by means of a shear-stress test.
Year: 2014
Number Pages:
7p.
Author(s): Tennent, N.; Calcutt , L.; Oliveira , T.; Overhoff, M.; Pereira, S.; Lookeren-Campagne, K.
: ICOM-CC 17th Triennial Conference Preprints, Melbourne, 1519 September 2014, ed. J. Bridgland
Editor: International Council of Museums- ICOM-CC
Keywords: Ceramic tile conservation; Cement pastes; Zinc hydroxychloride; Lithos Arte ®
Info
The history of Portuguese interior plaster coatings: A mineralogical survey using XRD
The evolution of the materials used in Portuguese interior wall coatings since the Roman occupation, namely the binders, is investigated using XRD in order to build a preliminary systematic database to contribute to the design and study of compatible products for conservation and repair. The results show that lime was the main binder until the end of the 18th century, with gypsum overcoming its use in the 19th century. A relationship is established between the results and several influencing aspects, namely other cultures, the neighbouring countries and their traditional construction techniques, the availability of raw materials, the purposes/techniques of application and the geographical location.
Year: 2014
Number Pages:
19p.
Author(s): Freire, T.; Santos Silva, A.; Veiga, M. R.; Brito, J.
: Archaeometry
Editor: Wiley
Keywords: Gypsum plaster; Xrd analysis; Mineralogical composition; Interior coatings; Lime plaster; Portuguese heritage
Info
The project RADE - Remote access to data and experiments. Application to hydraulic laboratory facilities
N/A
Year: 2014
Number Pages:
58-51pp.
Author(s): Lemos, R.; Fortes, C. J. E. M.; Capitão, R.; Wellens, P.
: Revista Hydrolink
Volume:
2/2014.
Info
The ReAVA project: assessment of the potential alkali-reactivity of volcanic aggregates from Azores Islands
Volcanic rocks have been found to be potentially alkali-reactive in a number of countries, including Japan, New Zealand, Iceland and Turkey. In order to characterize the potential reactivity of the volcanic rocks in Azores a project is being carried out, under the support of the Azores Government: the ReAVA ProjectCharacterization of Potential Reactivity of the Volcanic Aggregates from the Azores Archipelago: Implications on the Durability of Concrete Structures. This project comprises mainly: (1) petrographic assessment of the aggregates, (2) assessment of their performance in expansion tests and (3) site inspection of existing large concrete structures. This study has also the support of the IMPROVE ProjectImprovement of Performance of Aggregates in the Inhibition of Alkali-Aggregate Reactions in Concrete, aiming to minimize the occurrence of alkali aggregate reaction (AAR) in Portugal. The Azorean rocks used as aggregates are mainly basalts and some trachytes. The reactivity of this kind of rocks is usually associated with the presence of volcanic glass, altered minerals and SiO2 content of the rock. The petrographic examinations of the rocks confirmed that one of the basaltic samples contains volcanic glass. The occurrence of microcrystalline quartz as a secondary product filling the interstices of the trachyte sample was confirmed by scanning electron microscope. The results of the concrete expansion test RILEM AAR-3 showed an increasing expansion starting on 140 days and continued to grow after 2 years of laboratory testing, but below the limit of 0.05 % recommended for this method.
Year: 2014
Number Pages:
51-54pp.
Author(s): Medeiros, S.; Nunes, J. C.; Katayama, T.; Fernandes, I.; Santos Silva, A.; Miranda, V.; Soares, D.
: Urban Geology, Sustainable Planning and Landscape Exploitation
Editor: Springer
Volume:
5.
Keywords: Expansion tests; Petrography; Volcanic aggregates
Info
The role of non-linear dynamic soil-foundation interaction on the seismic response of structures
In this paper we provide an overview of recent research work that contributes to clarify the effects of non-linear dynamic interaction on the seismic response of soil foundation-superstructure systems. Such work includes experimental results of seismically loaded structures on shallow foundations, theoretical advancements based on improved macro-elementmodeling of the soil-foundation system, examples of seismic design of bridge piers considering non-linear soil-foundation interaction effects, and numerical results of incremental non-linear dynamic analyses. The objective of this paper is to support the concept of a controlled share of ductility demand between the superstructure and the foundation as a key ingredient for a rational and integrated approach to seismic design of foundations and structures.
Year: 2014
Number Pages:
1157-1176pp..
Author(s): Correia, A.A.; Pecker, A.; Paolucci, R.; Chatzigogos, C.; Figini, R.
: Bulletin of Earthquake Engineering
Editor: Springer
Volume:
Vol. 12, Issue 3.
Keywords: Incremental dynamic analysis; Displacement-based seismic design; Non-linear macro-element; Experimental testing; Seismic foundation response; Non-linear dynamic soil-structure interaction
Info
The whole and the parts: can lime coatings enhance the drying of salt laden materials?
Lime coatings are frequent in the architectural heritage. Previous research showed that they can accelerate the drying of porous materials, such as stone and mortars, which could help control the endemic problems of dampness of these constructions. Here, we investigate the effect lime coatings have in presence of soluble salts. The work is based on evaporation tests performed on one lime coating applied on five materials contaminated with solutions of NaCl or Na2SO4. Conclusions could be drawn about: (i) the behavior of the coating; (ii) the salt decay process. It was observed that the coating can, in few cases, still enhance drying when salts are present. However, in comparison to pure water, the drying kinetics is slower, more irregular and shows higher dispersion. Also, it sometimes diverges among specimens of the same material subjected to similar experimental conditions. These chaotic variations are in agreement with the decay patterns and suggest that soluble salts amplify the effects of the natural heterogeneity of porous materials.
Year: 2014
Number Pages:
179189pp.
Author(s): Gonçalves, T. D.; Brito, V.; Musacchi, J.
: Construction and Building Materials
Editor: Elsevier
Volume:
57.
Keywords: Sodium sulphate; Sodium chloride; Soluble salts; Porous building materials; Drying; Historical buildings; Architectural heritage; Limewash; Lime coating
Info
Thermal Influence on Long-Distance Optical Measurement of Suspension Bridge Displacement
This paper discusses the thermal influence on long-distance and noncontact measurement of suspension bridge three-dimensional displacement by the use of an optical system composed of a digital camera, infrared active targets, and computational support. ln this type of measurement method, the optical propagation path of light through the air can range from 250 m up to 750 m, making its measurement accuracy strongly dependent on atmospheric refraction and turbulence, phenomena that are linked to the vertical temperature gradient between the camera and targets. ln addition, the adopted measurement geometrical configuration can lead to a height difference between these two elements (camera and targets) above 50 m. The paper describes the experimental setup and procedure followed for the determination of local temperature vertical gradients in the 25th of April Bridge in Lisbon (Portugal), where an optical measurement system was applied. The obtained thermal measurements are presented and applied in the evaluation of the systematic refraction vertical deviation, based on appropriate mathematical models mentioned in the paper, and for the identification of stable or unstable observation thermal conditions related to turbulence.
Year: 2014
Number Pages:
19pp.
Author(s): Lages Martins, L.; Rebordão, J.; Ribeiro, A.
: International Journal of Thermophysics
Volume:
35.
Keywords: Displacement; Temperature; Suspension bridge; Optical system
Info
Transition zones to railway bridges: Track measurements and numerical modelling
Railway tracks degrade faster at transition zones to railway bridges. In modern lines, back
Year: 2014
Number Pages:
435-443pp..
Author(s): Paixão, A.; Fortunato, E.; Calçada, R.
: Engineering Structures
Editor: Elsevier
Volume:
80.
Keywords: Train
|