Structural Performance Assessment of Innovative Hollow Cellular Panels for Modular Flooring System

Lightweight modular construction has become an increasing need to meet the housing requirements around the world today. The benefits of modular construction ranging from rapid production, consistency in quality, sustainability, and ease of use have widened the scope for the construction of residential, commercial, and even emergency preparedness facilities. This study introduces novel floor panels that can be flat-packed and built into modular housing components on-site with minimal labour and assistance. The flooring system uses hollow cellular panels made of various configurations of trapezoidal steel sheets. The structural performance of three different configurations of these hollow flooring systems as a modular component is presented in this study by analysing the failure modes, load-displacement parameters, and strain behaviour. The study confirms significant advantages of the proposed hollow floor systems, with multi-cells reporting higher load-carrying capacity. The hollow flooring system performed well in terms of structural performance and ease in fabrication as opposed to the conventional formworks and commercial temporary flooring systems. The proposed flooring system promises efficient application as working platforms or formworks in temporary infrastructural facilities and emergency construction activities.

Improving the Performance of Structural Members by Incorporating Incinerated Bio-Medical Waste Ash in Reinforced Geopolymer Concrete

This study aims to analyze the use of Incinerated Bio-Medical Waste Ash (IBWA) in reinforced concrete structural member with ground granulated blast furnace slag (GGBS) as an alternate building ingredient instead of cement. Biomedical waste was produced from various medical resources such as hospitals, medical institutes and research centres. GGBS is the waste generated from the steel plant. The climate is now being affected by the release of CO2 (global warming) from the Portland cement industries. Therefore, greater attention must be paid to study efforts to use geopolymer concrete. Geopolymer is a novel inorganic eco-friendly binding agent derived from an alkaline solution that stimulates aluminosilicate source material (GGBS, Rice Husk Ash, Quartz Powder, metakaolin, fly ash and Silica Fume). In this research, laboratory tests for Reinforced Geopolymer Concrete (RGPC) beams (deflection, ductility factor, flexural strength and toughness index) and columns (load-carrying ability, stress-strain behaviour and load-deflection behaviour) were conducted for three types of proportions using [30% IBWA – 70% GGBS Geopolymer concrete, GGBS Geopolymer concrete and Reinforced Cement Concrete. The experimental findings revealed that the performance of reinforced 30% IBWA – 70% GGBS geo-polymer beams and columns worked more effectively than reinforced cement concrete beams and columns.

Effect of Fibre Reinforcement on Creep in Early Age Concrete

This research analyses the strain behaviour of fibre-reinforced concrete (FRC) in the event of a creep episode. The analysis of creep experienced by FRC specimens during the test reflects better performance than that predicted by the EHE-08 standard. The authors propose a formulation for the evaluation of creep strain undergone by FRC. During the research, the evolution of the modulus of elasticity of FRC after a creep episode is analysed. After the test campaign, it can be concluded that FRC loaded at an earlier age stiffens after a creep episode. After the creep test is completed, the delayed elastic strain undergone by FRC is analysed and it is observed that FRC loaded at an earlier age undergoes less deformation. The authors propose a formulation for the evaluation of the delayed elastic strain undergone by FRC after a creep episode.

Modeling of critical strain for dynamic recrystallization of niobium microalloyed steels

The critical strain for dynamic recrystallization (DRX) is most important in designing rolling schedules for the refinement of grain size by boundary-induced transformation mechanisms. Modeling of the critical strain for DRX from the stress-strain curves obtained from hot compression was physically built in this paper. The stress-strain behaviour of materials during hot deformation should be a combination of work-hardening and recrystallization softening. Before DRX occurred, the stress-strain behaviours could be described by a constitutive equation in which basic strain hardening and the effect of strain rate and temperature on stress-strain behaviour are included. Once DRX was promoted, obvious deviation between the experimental and calculated stress-strain curves appeared, which denoted the critical strain for DRX. The modeling in this work could be used not only to accurately calculate the critical strain for DRX but also to analyze the dynamic softening behaviours during hot deformation. To validate the calculated results, the stress-strain database was analyzed in the H beam sample deformed at 1000C with a strain rate of 0.1/s, and a critical strain of 0.22 was obtained by this novel method as an example. The calculated result is in good agreement with the experimental data obtained by micrographical observations.

Stress–Strain Behaviour of Reparable Composite Panel with Step-Variable Thickness

There is an urgent problem of finding an economically viable method of maintenance and restoration of the bearing capacity of structures of various applications. Repair of structures with patches made of polymeric composite materials is one of the most promising repair technologies. However, an improper choice of parameters of the composite patch leads to unjustified increase in the structure mass and the cost of its further operation. These situations result from the lack of reliable methods for developing the repair process, which take into account the influence of the patch geometry and conditions for performance of repair works on the bearing capacity of the repaired structure. The mathematical model of the reparable composite shell–type panel taking into account inhomogeneity of transverse shear deformations at stepped variation of its thickness has been developed. In contrast to the classical theory of layered shells, the model allows simplifying a three-dimensional problem by setting of the displacement field on the layers’ interfaces and their linear interpolation over thickness of the panel, as well as considering the transverse shear deformations resulting from the strength, temperature, or shrinkage loading. According to results, the maximum rise in stresses in the case of a notched panel occurs in the weakened layer, and it is from this layer the failure of the structure will start. In the event of the patch, the panel surface opposite the reinforcement is the most loaded (i.e., susceptible to failure) surface. To confirm the reliability of the developed model, we compared the analytical calculations with the results of experimental and numerical studies of the deformed state of a panel of step–variable thickness by the method of holographic interferometry and modelling by the finite element method. Displacement fields available from experiments correspond to the predicted theoretical results. The resulting maximum error does not exceed 7%. The data obtained during numerical modelling allowed us to conclude that the accuracy of theoretical calculations is sufficient for engineering practice. Results of the work can be used to solve the practical problems such as determination of stress–strain behaviour of a damaged structure or structure after repair, specification of the permissible delamination dimensions, and defining of parameters of the bonded repair process.

Mechanical Behaviour of a Residual Soil from Ignimbrite Rock of São Miguel Island - Azores

Azores consists of nine islands and several islets, located in the North Atlantic to 1600 km from Continental Portugal and is distributed between latitudes 36° 55' to 39° 43' N and longitude 24° 46' to 31° 16' W. Azores archipelago is in a convergence zone of a series of dynamic tectonic structures, that are responsible for seismicity and volcanism, geological and petrological of these islands. The island of São Miguel, an eastern group, in addition to other petrology’s in its geology, has ignimbrite, which is a pyroclastic rock with a dacitic or rhyolitic composition, resulting from the deposition of materials in semi-melting at high temperatures from a pyroclastic flow. At the site of Água D’Alto, the residual soil sample resulting from the ignimbrite alteration was taken and was evaluated with the interest of studying its application or use as construction material. The soil was subjected to physical and chemical classification test, compressibility, and stress-strain behaviour. This material shows good mechanical characteristics, although its chemism is potentially corrosive.

Compressive Strength of Steel Fiber Reinforced Polymer Modified Recycled Aggregate Concrete

Demolish existing structures for better economic gains, functional and structural performance, and non-availability of land or disposal sites in nearby areas of all major cities worldwide turned as a significant reason for the crushing demolished concrete instead of using it as landfill. Research work aimed at arriving Recycled Concrete (RC) with the help of two materials, i.e. Steel Fibers (SF) and Styrene-Butadiene Rubber (SBR) latex, as additives to improve strength parameters of it. SF and SBR added in RC to examine & strengthen and termed as Steel Fiber Reinforced Polymer Modified Recycled Aggregate Concrete (SFRPMRAC). For this purpose, 198 cubes each of M20 (trial-1) and M25 (trial-2) cast separately to check compressive strength and its stress-strain behaviour for Natural Concrete (NC), RC & SFRPMRAC. The volume fractions of SF added 0.5%, 1% & 1.5% m3 of concrete and dosages of SBR latex varied from 2.5%, 5% and 7.5% by cement weight for preparation of cubes made of RC. From experimental results, SFRPMRAC with SF volume fraction of 1% m3 of concrete and 5% by cement weight provides an improvement in compressive strength by 8.62 % & 10.73 % for trial -1 and 11.51 % & 12.57 % for trial - 2 at 28 & 90 days when compared with NC. Compression stress-strain behaviour for SFRPMRAC with SF 1% m3 of concrete and 5% by weight of cement shows higher strain values at the peak stress. SFRPMRAC arrests the sudden drop of load due to co-matrix bond formation between SF and SBR in a linear direction compared to a similar NC & RC mix for both trials. It reflects significant improvement and approval of compressive strength for the desired purpose.