Computational Analysis of the Forces Distribution in a Metal Frame Structure Taking into Account Plastic Deformations of the Material

Постановка задачи. С целью снижения материалоемкости строительных конструкций нормативные документы рекомендуют учитывать пластические свойства стали в прочностных расчетах. Это требует развития соответствующих методов расчета с применением современного программного обеспечения. Результаты. Усовершенствована методика расчета плоского стального рамного каркаса на статическую нагрузку на основе принципа предельного равновесия с применением программно-вычислительного комплекса «ЛИРА». Исследован поэтапный характер разрушения конструкции при воздействии сверхнормативных нагрузок. Выводы. Показано, что применение пошагового метода нагружения позволяет моделировать поведение конструкции в ходе увеличения нагрузки. Проведенные исследования позволяют давать верхнюю оценку максимально возможной нагрузки, возникающей в исключительных условиях эксплуатации. Statement of the problem. In order to reduce the material consumption of building structures, in regulatory documents it is recommend that the plastic properties of steel in strength calculations are taken into account. This requires the development of appropriate calculation methods by means of modern software. Results. The method of calculating a flat steel frame structure for static load based on the principle of limiting equilibrium using the design-computational complex LIRA has been improved. The gradual nature of structural failure under the influence of excessive loads is studied. Conclusions. It is shown that the application of the step-by-step loading method makes it possible to model the behavior of the structure during an increase in load. The studies allow us to provide an upper estimation of the maximum possible load that occurs under exceptional operating conditions.

Optimization of concentrically braced steel frame structures based on SNI 1726:2019, SNI 1727:2020, SNI 1729:2020, and AISC 341-16

Damages resulted from earthquakes are a loss in the economic sector. The structure of multi-story buildings needs an earthquake-proof design with higher performance to reduce such losses. By utilizing the metaheuristic algorithm, this study aims to identify the most compatible brace configuration and profile used in a concentrically braced steel frame structures with minimal total weight and that will meet the safety requirements. This algorithm is suitable owing to the fact that it is able to find solutions to any known optimization problem either through Particle Swarm Optimization (PSO), Symbiotic Organisms Search (SOS), or Differential Evolution (DE). The performance of these algorithms will demonstrated in a form of comparison through a case study of optimizing a 5-span, 6-story steel frame structure. These systems will determine the lightest frame weight, which also correlates to a lower construction cost, without compromising the constraints of SNI 1726:2019, SNI 1727:2020, SNI 1729:2020, and AISC 341-16. Based on the results of data processing, SOS is shown to achieve the highest algorithm performance compared to PSO and DE.

Experimental Study on Impedance-Based Damage Detection Considering Temperature Effect

The impedance-based damage detection technique has the potential for health monitoring of different types of structures. However, it is necessary to consider the temperature effect on the impedance signal in applying this technique to actual structures. In this study, an effective impedance-based damage detection method that compensates for the temperature effect was developed. Experimental tests on a steel frame structure connected with high tensile bolts were performed. Moreover, the temperature effect on the impedance damage index was compensated for detecting damage caused by bolt looseness; that is, the relationship between the impedance damage index and the temperature was established through long-term measurements. Based on this relationship, damage detection was performed by compensating for the temperature effect. Because the damage index after the bolt loosening reflects the effects of temperature and damage, it is difficult to evaluate the damage by monitoring only the damage index. However, after compensating for the temperature effect, it was observed that the damage could be estimated precisely. The damage was effectively monitored after measuring the impedance signal and temperature over a specific period for the initial healthy structural state, analyzing the correlation between the impedance damage index and temperature, and setting an appropriate warning criterion based on the correlation.