Concrete is the most consumed material in the construction industry. Using recycled aggregates (RA) and silica fume (SF) in concrete and mortar could preserve natural aggregates (NA) and reduce CO₂ emissions and construction and demolition waste (C&DW) generation. Optimizing the mixture design based on both fresh and hardened properties of recycled self-consolidating mortar (RSCM) has not been performed. In this study, multi-objective optimization of mechanical properties and workability of RSCM containing SF was performed via Taguchi Design Method (TDM) with four main variables including cement content, W/C ratio, SF content and superplasticizer content at three different levels. SF was used to decrease the environmental pollution caused by cement production as well as compensating the negative effect of RA on the mechanical properties of RSCM. The results revealed that TDM could appropriately predict the workability and compressive strength of RSCM. Also, mixture design containing W/C = 0.39, SF = 6%, cement = 750 kg/m³ and SP = 0.33% was found as the optimum mixture having the highest compressive strength and acceptable workability as well as low cost and environmental concerns.

In this paper, the seismic response control of offshore jacket-type platform equipped with Shape Memory Alloy (SMA) braces is investigated. Concerning the properties of the SMAs, a new connection is introduced in order to make the most of it. Based on an actual platform structure and its mechanical model, the optimized localization of SMAs are found by damage propagation under pushover loadings. To evaluate the possibility of adopting the innovative bracing system and its efficiency, the dynamic responses of 3-D model of the existing 4-legged offshore platform placed in Persian Gulf (SPD12) is compared to the ones with SMA braces. The results show that using an SMA element is an effective way to develop the API recommendations and improve the dynamic response of offshore platforms subjected to earthquake excitations. Implementing the SMA braces can lead to a reduction in residual displacement, deck level displacement, elements and connections forces, and base shear compared to the steel tubular braces model.

In this paper, optimum parameters of Tuned Mass Dampers (TMD) are considered to control the responses of 10-story shear building under harmonic loading and 22 set of seismic records of FEMA-P695. The criterion used to obtain the optimum parameters is to select mass ratio, the frequency (tuning) and damping ratio that would result in smallest lateral displacements. State-space equations of motion are presented to compute the structural responses by developing a MATLAB file. A 10-story shear building is presented as a case study to assess the effects of TMDs on the multi-story structures. The results indicate that using TMD can reduce structural responses up to the average 20% under earthquake excitation and up to 90% under harmonic loadings. TMDs are not always effective under any type of ground motion; therefore, being aware of the given location is significant to design TMDs properly.