Selecting the appropriate wavelet function in the damage detection of precast panel building based on experimental results and numerical method

Most building structures are damaged over time under environmental conditions and external loads. In this regard, the occurrence of damage is common and the detection of damage is the subject of much research. In this regard, wavelet conversion, which is a powerful mathematical tool for signal processing, has attracted the attention of many researchers in the field of health monitoring. In this study, free vibrations of a four-story building with specified boundary conditions and monitored the health of the building based on experimental results using the continuous wavelet analytical method are studied and the damage that may occur in these structures were evaluated and analyzed. The finite element software is used to Model of the Building by the sandwich model. In this four-story building, eight-layer sandwich panel (polystyrene, concrete, steel, concrete) is used symmetrically. The fourteen natural frequencies of the sandwich structure were compared with the experimental model and the main modes of the structure were obtained to influence the health of the structure. An error of less than 2.5% reveals a good match between the results of the two models. Precast panel health monitoring results show that based on the experimental results, the damage location using the coif5 function with scale parameter 8 has been successfully identified and showed a higher perturbation of the coefficients at the damage locations than the other functions. Thus, the relative maximum and minimum jumps in the wavelet coefficients occurred at the location of the damage and considering the maximum or minimum wavelet coefficients generated at the damage location as the center of damage, the damage center can be identified with an error of less than 8%. Also, effects of higher modes are more pronounced in the damage intensity index as in the torsional modes of the structure, the maximum wavelet coefficients are greater and the intensity of the damage more pronounced

Evaluation of shear behavior of sandwich panel shotcreted by low-cement material

In modern life, with the advancement of science and technology, human need for prefabricated structures is felt more. Therefore, the study of prefabricated structures becomes very important. Lightweight prefabricated structures are among the items that need further studies and researches. These panels have high execution speed and are earthquake resistant. These elements are used as wall and ceiling in structures. It is necessary to study the shear capacity and performance of these lateral panels against and reciprocating loads. In this study, the compatibility of prefabricated structures with nature and reduction of maximum pollution have been considered. For this purpose, an attempt is made to use materials compatible with nature and replace them with cement. This study is a laboratory study of the lateral bearing capacity of lightweight prefabricated panels and its integration with the desired materials. Five shear walls consisting of a thatched specimen and two specimens are made using bentonite. A one-story structure with bentonite was also examined and reinforced. The results of the samples are presented in the form of hysteresis curves and push finally hardness diagram. Finally, the results are compared. The sample with a cement grade of 400 had the highest load capacity and was able to withstand 52.33 kN load. Also, the straw sample suffered the least load. The highest difficulty is related to the sample of a one-story building, followed by the cement sample with a grade of 400. The straw sample has the least hardness. The decrease in stiffness occurred in the samples with a steep slope. The amount of energy absorbed by each sample is equal to the area under the cover curve. The sample with a grade of 200 cement has the highest area under the curve, thus absorbing the highest amount of energy. The thatch sample absorbs the least amount of energy. The average ductility of a single-story structural sample is higher than that of other samples. The thatched specimen has the lowest ductility

Application of life cycle assessment approach to deliver low carbon houses at regional level in Western Australia

Purpose: Australian building sector contributes 23% of the total greenhouse gas (GHG) emissions. This is particularly important for Western Australia (WA) as the houses here are made of energy- and carbon-intensive clay bricks. This research has utilized life cycle assessment (LCA) approach and cleaner production strategies (CPS) to design low-carbon houses in 18 locations in regional WA. Methods: An integrative LCA analysis of clay brick house has been conducted by incorporating energy efficiency rating tool (i.e., AccuRate) to capture the regional variation in thermal performance of houses in 18 locations in WA under five climatic zones. The data bank provided information on energy and materials for mining to material production, transportation of construction materials to the site of construction, and construction stages, while an energy rating tool has been utilized to generate location-specific information on energy consumption during use stage for developing a life cycle inventory for estimating life cycle GHG emissions and embodied energy consumption of a typical 4 × 2 × 2 detached house (i.e., 4 bed rooms, 2 bathrooms, and 2 cars/double garage). This approach has enabled us to determine the location-specific hotspot of a house in order to select suitable CPS for achieving reduced level of GHG emissions and embodied energy consumption. Results and discussion: Except for two hottest locations, the average life cycle GHG emissions and embodied energy consumption of houses at 16 locations in regional WA have been estimated to be 469 t of CO2 equivalent (or CO2 e-) and 6.9 TJ, respectively. Home appliances and water heating have been found to be the top two hotspots. The CPS options, including rooftop solar photovoltaic panels (PV), solar water heaters (SWH) integrated with gas based water heaters, cast in situ concrete sandwich wall, fly ash as a partial replacement of cement in concrete, and polyethylene terephthalate (PET) foam made of post-consumed polyethylene terephthalate bottles, have been considered to reduce GHG emissions and embodied energy consumption of a typical house in18 locations in regional WA. Excluding above two hottest locations, these CPS provide an opportunity to reduce GHG emissions and embodied energy consumption per house by an average value of 320 t CO2 e- and 3.7 TJ, respectively. Conclusions: Considering the alarming growth rate of the housing industry in WA, the incorporation of optimum house orientation, rooftop solar PV, roof top SWH, cast in situ sandwich wall, partial replacement of cement in concrete with fly ash, and PET foam insulation core could reduce the overall GHG emissions and embodied energy consumption associated with the construction and use of clay brick wall house which in turn will assist in achieving Australia’s GHG emission reduction target by 2050. The findings provide useful data for architects, designers, developers, and policy makers to choose from these CPS options based on existing resource availability and cost constraints