Numerical modelling of multiple tuned mass damper equipped with magneto rheological damper for attenuation of building seismic responses

TMD is basically designed to be tuned to the dominant frequency of a structure which the excitation frequency will resonate the structural motion out of phase to reduce unwanted vibration. However, a single unit TMD is only capable of suppressing the fundamental structural mode and for multimode control, more than one TMD is needed. In this study, a 3-storey benchmark reinforced structural building subjected to El Centro seismic ground motion is modelled as uncontrolled Primary Structure (PS) by including properties such as stiffness and damping. For the case of controlled PS which the passive mechanism is included to the system, optimum parameters of both TMD and Multiple TMD (MTMD) are designed to be tuned to the dedicated structural modes where the performance is dependent on parameters such as mass ratio, optimum damping ratio, and optimum frequency ratio. The input and output components of structural system arrangements are then characterized in the transfer function manner and then converted into state space function. For enhancement of the passive system, Magneto-Rheological (MR) damper is added to both single TMD and MTMD passive system. The response analysis is executed using both time history and frequency response analysis. From the analysis, semi-active case is the most effective mechanism with 99% displacement reduction for the third and second floors, and 98% for the first floor, compared to the uncontrolled case. It is concluded that the MR damper significantly contributed to the enhancement of the passive system to mitigate structural seismic vibration

Study on numerical analysis of high rise building

This paper presents the numerical study conducted on a structure of three floor height building structure. Most vibrations are undesirable and can cause damages to the buildings, machines and people all around us. The vibration wave from earthquakes, construction and winds have high potential to bring damage to the buildings. Excessive vibrations can result in structural and machinery failures. This failure is related to the human life and environment around it. The effect of vibration which causes failure and damage to the high rise buildings can be studied through the numerical analysis. This research aims to study the numerical analysis of high rise building through the simulation using MATLAB R2015a. A lumped mass model of three degrees of freedom (3DOF) is designed using MATLAB R2015a to identify the displacement, acceleration and mode shape of the 3DOF during vibration. The model designed is the physical representation of actual building structure in real life.The considered factors are the mass of the building and the stiffness of the structures scale which will be used for the simulation. Thus, the result obtained will be comparable with the real life effect. Based on the result from simulation study, by applying the forces of vibration on the building model the displacement, acceleration and mode shape can be analyzed. The result obtained can be used in future for further analysis during the experiment analysis

Utilizing silica fume for development of concrete strength

Corresponding to the introduction of silica fume in concrete improves both the mechanical and durability characteristics of the concrete. This thesis presents the results of research effort conducted at different percentage of silica fume in concrete. The program investigated various characteristics of silica-fume concrete. It emphasized the effect of silica fume on workability level and its maintenance of fresh concrete; strength development and strength optimization and of hardened concrete. The experimental program comprised four levels of silica-fume contents (as partial replacement of cement by weight) at 0% (control mix), 5%, 10%, and 15% without superplasticizer. Concrete mixture been designed by respecting to American Concrete Institute (ACI) method. Concrete cube specimens were tested using compression machine for curing age of 3, 7, and 28 days. It was found that there was an optimal value of silica-fume content at which concrete strength improved significantly. All data had been analyzed using mean statistical method and regression method. Due to the slow development of pozzolanic effect, there was a drop in early strength up to seven days and late significant gains up to 28 days upon introducing silica fume to concrete. As per design requirement, the control mixture batch achieved the targeted 28-day compressive strength of 35 MPa. Result of modified concrete designation indicates that 10 and 15 percent addition of silica fume batches stated the 28-day average compressive strength of 38.28 MPa and 40.66 MPa, significantly higher compared to control mix. However, the 5% added silica fume concrete batch showed unobvious increase in compressive strength with 35.62 MP