Seismic Strengthening RC Structures Approaches
Journal Title: Trends in Civil Engineering and its Architecture - Year 2018, Vol 2, Issue 3
Abstract
The method based on separation of the earth & structure. In this method applied force will be decreased during earthquake due to separation of structure & earth by making base of structure or floors flexible and applying energy dampers component & separator layer usually have a higher natural period than fixed support natural period which cause the acceleration of seismic spectrum to decrease and a kind of short cylindrical seismic cushion with one hole or more and steel plates with stiffen rubber between them are mundane in seismic separators and because of depreciation of energy by seismic separators and this method is used for stiff structures with high and short frequencies with heavy forces but in this technique the use of seismic separator in soft soils due to possibility of equalization of period and exacerbated phenomenon or Resonance isn’t recommended and choose period must be far from earth movement period, if it’s possible. The benefits of this method are: a. Producing suitable flexibility at structure. b. Decreasing drift of floors and Structural and non-Structural failures. c. Decreasing frequency of structure vibration and decreasing forces of seismic design. d. Needing less space of structure for performing this strengthening design. The Corrosion resistance and bearing of high thermal deformations. The isolators are used below or top of the foundation or at the bottom and axe of the columns or in the middle of the column. Use of energy dissipation: this method is based on increasing the damping and decreasing the oscillation amplitude and consequently reducing the seismic response. All types of dampers are friction, hysteresis, metallic, slurry, visco elastic. The main advantage of all of them is the ease of installing. In recent years the use of steel plates (tadas), divergent frames (EBF) and shear panel systems (SPS) have become more popular in Structural applications. Usually dampers are mounted on braces between the braces, the beams, between the walls or between the wall and the beam. Using the combined system of pre-tensioned cables and dampers 8-2 local restorative repair. The critical zone in the RC frames is the beam-to-column connection, where the shear failure occurs in the connection panel due to the lack of cross reinforcement concrete or steel armor and the use of FRP jackets or pre-tensioned tendons and ... is among the methods of restoring and local reinforcing RC members. Covering the Columns The shear failure of the RC column in the limited shape changes coupled with the loss of lateral load resistance is due to the fact that the shear strength of column related to its bending strength in cyclical and alternative load is more to decrease faster and the covering column with jacket also increases the shear strength both the bonding strength is effective and it increases the confinement and its effects on increasing of the ultimate strain of the concrete. The steel cage is constructed of corrugated sections in the longitudinal and transverse steel straps. In practice, the transverse strap is tangled sideways, using special wrenches or pre-heater members. An empty space between the steel cage and the existing concrete is usually filled with anti-shrinkage resistant mortars. It should be noted that the mortar should not have normal cement sand. Due to the agglomeration of the mortar, an early slippage occurs between the surface of the mortar and the concrete, which affects the increase in loading caused by the Confinement, and where we focus on the protection of steel against corrosion and fire, shotcrete would be used.
Authors and Affiliations
Kaveh Ostad Ali Askari, Vijay P Singh, Nicolas R Dalezios, Theodore C Crusberg
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