Advanced Materials Research Vol. 1119

Abstract: FRP-concrete-steel double-skin tubular columns (DSTCs) are a new form composite column system that effectively combines the advantages of the constituent materials. The performance of this column system has been experimentally investigated in a number of recent studies. However, apart from a single study reported on square DSTCs, all of the existing studies have been concerned with DSTCs with circular external tubes. This paper reports on part of an ongoing experimental program at the University of Adelaide on FRP-concrete-steel composite columns. The results from 12 square hollow and concrete-filled DSTCs and six companion hollow concrete-filled FRP tubes (H-CFFTs) that were tested under axial compression are presented. Results of the experimental study indicate that hollow DSTCs with larger inner steel tube diameters develop similar ultimate axial stresses to but significantly larger axial strains than companion DSTCs with smaller inner steel tubes. The results also show that, in concrete-filled DSTCs with similar D_s/t_s ratios, an increase in the steel tube diameter leads to an increase in both axial stress and strain of concrete. It was observed that H-CFFTs perform significantly worse than both hollow and filled DSTCs under axial compression, and their behavior further degrades with an increase in the diameter of their inner voids.

Abstract: The effective thermal conductivity is an important parameter used to predict the thermal performance analysis of complex structured porous building materials. The observation of porous structure of building materials on REV (representative elementary volume) scale showed that pores can be classified into meso and macro pores. In contrast to the traditional models usually used for the (macro-meso) pore connection , a new numerical random generation macro-meso pores (RGMMP) method, based on geometrical and morphological information acquired from measurements or experimental calculations, is proposed here. Along with proposed structure generating tool RGMMP a high efficiency LBM, characterized with the energy conservation and appropriate boundary conditions at numerous interfaces in the complex system, for the solution of the governing equation is described which yields a powerful numerical tool to obtain accurate solutions. Then present model is validated with some theoretical and experimental values of effective thermal conductivity of typical building materials. The comparison of present model and experimental results shows that the proposed model agrees much better with the experimental data than the traditional theoretical models. Therefore, the present model is not limited to the described building materials but can also be used for predicting the effective thermal conductivity of any type of complex structured building materials.

Abstract: The paper is part of a research that aims at investigating the relationship between fire and post-fire (i.e. residual) mechanical behaviour of masonry walls, paying attention to the possible exploitation of numerical tools for simplified approaches. The goal is to establish relationships between exposure severity under ISO834 conditions and decay in mechanical properties after exposure; the parameter of wall thickness is especially investigated, by choosing four different values (i.e. 12, 25, 38 and 51 cm). This is performed by means of FEM analysis with DIANA 9.4.4 software, simulating a standard ISO 834 fire resistance test followed by a mechanical compressive failure test on each investigated type of wall. The FE analyses’ outcomes allow to draw exponential expressions of the decay in compressive strength as a function of the exposure severity.

Abstract: The paper addresses the issues of fire behavior of masonry walls made of traditional/historical component materials (bricks and mortar). There are reasons for coupling investigations on the residual mechanical properties to fire resistance data, aiming at a more complete knowledge of the behavior of a masonry member during and after fire exposure. The paper is part of a research that aims at investigating the relationship between fire and post-fire (i.e. residual) mechanical behavior of masonry walls, paying attention to scale-related problems and to the possible exploitation of numerical tools to establish simplified approaches. The goal is to establish relationships between fire resistance ratings under exposure and decay in mechanical properties after exposure; the parameter of wall thickness is especially investigated, by choosing four different values (i.e. 12, 25, 38 and 51 cm). This is performed by means of FEM analysis with DIANA 9.4.4 software, simulating a standard ISO 834 fire resistance test followed by a mechanical compressive failure test on each investigated type of wall. The approach, successfully tested against experimental data already available, features a preliminary transient heat flow analysis which gives a numerical prediction of fire resistance after violation of I (Insulation) criterion; then, a staggered heat flow - stress analysis repeats the heating of the wall up to insulation failure and calculates the thermal strain accounting for cracking; finally, a ‘cold’ structural analysis in compression is performed on the thermally-deformed model after cooling. The paper also addresses a way for the extended application of the research outcomes, relying on a simple approach based on the concept of equivalent fire severity.

Abstract: Prestressed concrete girder bridges are one of the most widely used bridges in the world because of their excellent construction feasibility, economic efficiency, serviceability, and safety. In certain situations, however, the prestressing tendon is supposed to be bent locally, and this leads to the loss of prestress force. This kind of prestress loss is not considered in the design and construction processes. This study shows that prestress loss occurs at the locally bent tendon, and that a 2% maximum of prestress loss occurs at the locally bent tendon, due to eccentricity.

Abstract: This paper presents the results of the experimental research performed on the pultruded FRP (PFRP) channel beams subjected to transversely concentric and eccentric loads. The objectives of the research work are to investigate their structural behaviors and to determine the critical buckling moments and modes of failure of the beams with various span-to-depth ratios and eccentricities. Pultruded beams are fixed-end supported at both ends for major and minor-axis flexure. The beam specimens have the cross-sectional dimension of 102×29×6 mm with span-to-depth ratios, ranging from 20 to 40. A total of 40 mono-symmetric section tests were performed. The effects of vertical load position through the cross-section were studied. Also, shear center position with concentric load and three different eccentricities were investigated ranging from 0 to-3e. The specimens were tested to final buckling. Based upon the results of this study, it is found that the load versus mid-span vertical deflection relationships of the beams are linear up to the failure. On the contrary, the load versus mid-span lateral deflection relationships are geometrically nonlinear. The general mode of failure is the flexural-torsional buckling. The eccentrically loaded specimens are failed at buckling loads lower than their concentric counterparts. Overall, the critical buckling moment decreases as the magnitude of eccentricity increases. Additionally, it is noticed that L/d ratio increases, the critical buckling moment is decreased.

Abstract: Granulated Blast furnace Slag (GBS) has good potential to be use as granular material in place of conventional granular materials i.e. sand and aggregate. It can be use as structural fill in low laying areas. In such cases, it is required to evaluate the bearing capacity of the fill and reinforced it with some suitable reinforcing materials to enhance the bearing capacity. In this study, Response of circular footing was studied by using GBS as fill material and geogrid as reinforcing material. Only one geometric parameter i.e. number of geogrid layers was considered to get the response of circular footing. Two numbers of geogrid layers were obtained as optimum parameters and it increases the ultimate bearing capacity 94% and decreases the settlement by 45% as compared to unreinforced GBS bed.

Abstract: In this work, the subbituminous fly ash (SFA) in Thailand has been investigated for their compositions and crystal structures. Borosilicate glasses were prepare from SFA , B₂O₃, Na₂O and various concentration of Fe₂O₃ by melt quenching technique. The results have shown that the chemical composition comprised with SiO₂, Al₂O₃ and Fe₂O₃. The crystal structures of SFA were raised of mullite and quartz phases. The density and refractive index values of glasses were found to increase with increasing of Fe₂O₃ concentrations. The hardness values have been decreased with increasing of Fe₂O₃ content. The absorption spectra are corresponding to ferric and ferrous ions in wavelength of 440 nm and 1,050 nm and the color of glasses are green to yellow.

Abstract: This study aims at presenting a methodology for the taking decision about the retrofit or the destruction of the damaged buildings by an earthquake. The proposition is founded on the damages caused by the seism of Boumerdes in Algeria, on 23 May 2003. This work can to help the authorities and owners to make a choice concerning the retrofit or the destruction of buildings and reconstruction.The analysis begins by the identification of the structural damages in the structures, then by the evaluation of costs of the reparations and the retrofit of all functions of the building. If the owner has contracted insurance, the amount of insurance is deducted. After this step, this cost is compared to the cost of the destroying of the old building and the rebuilding cost of a new similar building. The life duration of structure is integrated respectively for the retrofitted building and the build of a new equivalent building. The depreciation of capital according to the time of exploitation is calculated on the reference: fifty years for the new investments, and twenty-five years for the retrofitted buildings.The resolution of the problem uses the comparison between the cost of retrofit divided by twenty-five to which added the amount of insurance, and the cost of new equivalent construction divided by fifty to which added the amount of destruction. This approach gives a result according to retrofit, insurance, the equivalent new building and the depreciation of capital. The compilation of the actualized costs according to each zone permits to have a quick vision about the economical decision. The cost of the urban land component is not taken in account and the network is considered in good state.

Abstract: Net Zero Energy Building (Net ZEB) concept has been applied to make a selected building as a self-energy provider. The building was partly modified to reduce its energy consumption using several energy efficient technologies such as wall material, insulator, VRF air condition unit, solar lighting, LED light bulbs, etc. While, electricity served into the building was generated by solar energy (PV panels). The monitored data over one year have proved that this build can generate the electricity more than its energy demand. This is a good achievement of Net ZEB in Thailand.