Traditional shape and stress control of structures use many actuators and require enormous time to find reasonable solutions that need designers to input specific target displacement and stress. This ...study employs a linear technique to static shape and stress control of pin-jointed assemblies as a theoretical advancement to prior works and provides a comparative analysis against previously established works. The study evaluates the proposed method using MATLAB to find the optimum set of actuators, and MATLAB and SAP2000 to verify the actuation results obtained through applying the set of actuations to the numerical models. The proposed method minimizes the number of trials, count of actuators, and total actuation up to 83%, 73%, and 50%, respectively. Furthermore, the optimum solution could be found in a single trial. The study focuses on the three aspects: (a) finding the optimal count of actuators; (b) optimum amount of actuation using fmincon function; and c) Implementing two-sided inequalities to control equations allowing designers to develop target internal forces and nodal displacements, as domains rather than specific numbers. This improves the optimization process affecting actuator count, total actuation elements, and processing time.
This paper investigates the flexural behavior of high-strength RC beams experimentally to assess the effect of Nano-silica (NS) and Macro-Synthetic High Strength Polypropylene Fiber (MPF). Ordinary ...Portland cement was partially replaced by the NS and MPF with different proportions to produce four concrete mixtures. Tests were conducted on the full-scale high-strength RC beams, including first crack load, failure load, deflection, concrete strain, steel strain, and mode failure, which were examined and compared. In addition, the tests on the mechanical properties of high-strength concrete mixtures were also conducted at the ages of 28 and 56 days. The test results concluded that the addition of NS and MPF significantly improved the first-cracking and failure loads and decreased deflection at levels of cracking and failure loads. Additionally, an increase in NS content resulted in a minor increase in the ultimate strain related to the failure loads. Furthermore, the mix of 3% NS with 0.5% MPF was found to lead to the highest mechanical characteristics of concrete. The improvements were the concrete compressive strength by 33.6%, split tensile strength by up to 54.1%, and flexural strength by up to 28.3% compared with control specimens.
Lightweight structures comprise of actual pieces or segments that give the crucial ability to function while weighing less than other possibilities as well. The aerospace industry invented this ...particular branch of expertise, which is sometimes referred to as lightweight engineering or lightweight construction. This paper focuses on how lightweight structures are developed and applied in the field of structural engineering which is essential to achieving the high standards and breakthroughs of modern science. Comparison is made depending on different types of lightweight materials such as titanium alloys, shape memory alloys, magnesium, aluminum alloys, and wood composites, benefits, and applications of each type of material are discussed. Recent technologies and innovations in the field of lightweight design are performed including deployable and morphing structures, 3D printing, embedded sensors and actuators, and advanced joining technologies. Moreover, research is also being done on these structure types of evolution, uses, and significance, as well as their design techniques and innovations. Truss, tensegrity, pantographic, cable, origami, and sandwich structures are identified by explaining their properties and working mechanisms. The usage of several lightweight structures in the fields of aerospace, robotics, civil engineering, architecture, automotive, and biomedicine is examined in this paper. Additionally, the comparison is made between the application of tensegrity, truss, pantographic, and sandwich structures in aircraft applications in detail, while the importance of shape morphing and deploying of pantographic and origami structures is explained in the field of aerospace and robotics. In addition, different types of bridge structures and architecture are mentioned according to applications of suspension cables, stayed cables truss structures, and tensegrity techniques. Furthermore, the paper covers the improvement of computational and numerical techniques in the analysis and design of lightweight structures including the force method, dynamic relaxation method, and finite element method (FEM), trends in optimization techniques and their applications are included mentioned sequential quadratic programming (SQP) and interior point optimization, with applications on different types of lightweight structures. Also, perspectives and future directions of lightweight design through sustainability and smart construction are taken into account, importance of lightweight design in the form of environment and innovation is clearly supported.
The tendency to build cable arch stayed bridges is increasing due to their aesthetic appearance and efficient performance. Due to overloading or time passing, they may face deformation thus they are ...required to be reshaped. For the same explanations the cables could undergo high tension and some others face slack, in order to keep the bridge safe in terms of stress failure, the redistribution of internal force of cables is essential. Pragmatically, the displacement restoring and the force redistribution are simultaneously necessary, since both issues arise together. This paper deals with simultaneous control of nodal displacement and internal force of cable theoretically by MATLAB Program and experimentally of a linear and a geometrically nonlinear model. The paper also shows that how the technique of adjustment response to control linear and geometrically nonlinear structures. It was determined that the technique was pragmatic and effectual for linear structures. While it was not very accurate for geometrically nonlinear structures, since more than one iteration was required to get the target.
The defective structures must be retrofitted to resist the effects of earthquakes due to the potential risks connected with reinforced concrete structures designed in many parts of the world in ...accordance with codes that are now proven to guarantee insufficient safety against seismic loads. Typically, shear walls or steel bracing are utilized to boost the seismic strength of framed structures. This paper discusses the possibility of using braces in two different conditions, the first one is in retrofitting already constructed structures that don’t have sufficient strength against seismic loading, and the second one is the possibility of using braces instead of shear walls in designing non constructed reinforced concrete structures for economical purposes. Different bracing systems in different locations compared with reinforced concrete shear walls in affecting the structural properties of the 10-story square building. Using bracing in the interior frames of buildings was also considered. The results show that different bracing systems have different responses for structural properties such as story displacement, base shear and fundamental time period. The results are significant for detecting the best bracing system to use instead of shear walls reflecting for the two mentioned scenarios as well as considering their locations on the building.
Chewed gum being left on streets is a common problem everywhere and it makes the environment totally dirty, which is so costly to clear. In this research, the chewed gum was collected and stored in ...the freezer in order to be very brittle and easily crushed to powder, which was passed through the sieve No. 16 (1.18mm). This study investigates cement replaced by chewed gum. Eight batches were prepared to show the effect of chewed gum on the mechanical properties of concrete, through replacing the gum powder by 0.25%, 0.50%, 0.75%, 1.25%, 1.50% and 1.75% of the weight of cement to compare with the conventional concrete for w/c=0.55. The samples were tested for compressive strength and splitting tensile strength at ages of 7 and 28 days. On the basis of the experiment results, it was concluded that in general the compressive strength and splitting tensile strength decrease by increasing the chewed gum content in the concrete mix, when cement is partially replaced by chewed gum for both ages 7 and 28 days.
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