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The purpose of this paper is to present weighted residual method (WRM) for evaluating damping ratio of unreinforced glued‐laminated (glulam) wood beams and also reinforced glulam beams with E‐glass reinforced epoxy polymer (GRP) plates.

In this method, created error from the regression curve to the peak points of experimental displacement values is minimized. Several weight functions such as Galerkin weight function, Petrov‐Galerkin weight functions, and least square weight function are used for minimizing this error and results from these methods are compared to the existing methods as; logarithmic decrement analysis (LDA), Hilbert transform analysis (HTA), moving block analysis (MBA), and half power bandwidth (HPB).

Because WRM tries to minimize the error function provided from differences between theoretical and experimental fitted curves, comparison among these methods indicate that proposed procedure is useful for any range of damping ratios and it gives better values in comparison with the other methods. Due to the initial conditions and weight function used in Galerkin weighted residual method, damping ratio values obtained from this method have different values from the other weighted residual methods. Among the existing methods, HPB method could not predict damping ratio of the glulam beams accurately.

This paper is a high quality research paper that presents weighted residual method (WRM) for evaluating damping ratio of unreinforced glued‐laminated (glulam) wood beams and also reinforced glulam beams with E‐glass reinforced epoxy polymer (GRP) plates. In this paper, LDA, HTA, MBA, and HPB methods are used and an analytical investigation of damping ratios of glulam beams unreinforced and reinforced with GRP plates is proposed by using weighted residual method (WRM). Although there is a simplifier assumption in some of existing methods, proposed method shows the damping ratio can be calculated without any requirement to simplifier assumption.

Today, using lightweight structural concrete plays a major role in reducing the damage to concrete structures. On the other hand, lightweight concretes have lower compressive and flexural strengths with lower impact resistance compared to ordinary concretes. The aim of this study is to investigate the effect of simultaneous use of waste glass powder, microsilica and polypropylene fibers to make sustainable lightweight concrete that has high compressive and flexural strengths, ductility and impact resistance.

In this article, the lightweight structural concrete is studied to compensate for the lower strength of lightweight concrete. Also, considering the environmental aspects, microsilica as a partial replacement for cement, waste glass powder instead of some aggregates and polypropylene fibers are used. Microsilica was used at 8, 10 and 12 wt% of cement. Waste glass powder was added to 20, 25 and 30 wt% of aggregates, while fibers were used at 0.5, 1 and 1.5 wt% of cement.

After making the experimental specimens, compressive strength, flexural strength and impact resistance tests were performed. Ultimately, it was concluded that the best percentage of used microsilica and glass powder was equal to 10 and 25%, respectively. Furthermore, using 1.5 wt% of fibers could significantly improve the compressive and flexural strengths of lightweight concrete and increase its impact resistance at the same time. For constructing a five-story building, by replacing cement with microsilica by 10 wt%, the amount of used cement is reduced by 5 tons, consequently producing 4,752 kg less CO₂ that is a significant value for the environment.

The study provides a basis for making sustainable lightweight concrete with high strength against compressive, flexural and impact loads.