Of the most important rubber bearings used in isolation structures are rubber bearings low or high damping or low damping natural rubber with lead core (LRB) [1] -[15] .

Is based on lead-core generate hysterical damping and hence power dissipation, also depends on the rubber in the generation of forces returns (Figure 3).

Based system for power dissipation on the friction generated between the composite material which usually consists of high strength material soily or gummy known as “PTFE” (poly tetra fluoro ethylene), and sliding surfaces of steel (stainless steel) (Figures 4-5).

Insulation systems are classified slider turn into two types: [8]

・ Spherical Sliding Bearing (Figure 4).

・ Pure friction system (Figure 5).

Proven experience and expertise previous that slider isolation systems, which rely horizontal sliding surfaces (Figure 5) cause large residual transitions in the structure because of the absence of mechanical forces return, so is the need for additional devices to Insurance Returns forces [11] . The insulation system that takes slider sliding surface (Figure 4) which form concave and thus secures a waste of energy, mechanical and return to the center after the excitement in the seismic isolation unit [1] -[8] [11] .

Recall of these systems:

Although the devices isolation seismic are manufactured typically with the ability to dissipate the energy and control to max move for device isolation, but there are situations we need to complementary mechanisms of the insulation system (dampers) to dissipate energy and to reduce the displacements [4] ,

Some of these cases [4] :

-The location is close to seismic source dominant.

-To be under the soil layers insulation systems of tor weak.

-The isolation devices are prone to instability in the light both sides of the large deformation.

-Architectural considerations that limit the seismic interval allowed.

-The practical limitstostructureservicesandtheirtowithstandgreatmoveforisolationsystem.

= Effective stiffness at design displacement.

= Effective damping coefficient Associated with design displacement.

The characterised strength (Q) is effectively equal to the yield force (F_y), of the lead plug. The yield stress of the lead plug is usually taken as being around 10 MPa. The effective stiffness of the LPB, at a horizontal displacement (D) being larger than the yield displacement (D_y) may be defined in terms of the post-elastic stiffness (KD,) and characteristic strength (Q), with the following equation (Figure 10) [11] :

The energy dissipated for one cycle of sliding, with amplitude (D) (Figure 10) can be estimated as:

The effective percentage of critical damping provided by the isolator (Figure 10) can be obtained from:

For Spherical Bearings:

Flat Bearings (Figure 11):: (1-8)

where:

µ: Coefficient of friction for the sliding.

W: Total seismic forces.

: Continued reference (Figure 11):

・ Bearings do NOT increase natural period of structure; rather they limit the shear force transferred into the superstructure (Figure 11) [11] .

・ Requires supplemental self-centering mechanism to prevent permanent isolation system displacement (Fig- ure 11) [11] .

Modeling of friction damper as spring form (Plastic Wen link [14] ) (Figure 12(b)),

The force in the Rotation Friction Dampers (FD) are determined in Figure 12(a) by the following equation:

[4] -[10] [12] -[14] (1-9)

z: hysteretic variable where, the initial value of z is zero.

F: forced, d: deformation, k: Stiffness, y: yield force, r: yield ratio.

The schematic as well as basic principle of the proposed damper are shown in Figure 13 and Figure 14, respectively [9] . The damper (FD) has several steel arms one ends of which are linked each other by a bolt in order for them to rotate freely, and carefully manufactured disk friction materials are embedded in that link. By connecting both ends of these arms to the upper and lower structures, horizontal deformation of the girder is converted into the rotational motion of the link and disk. To be more precise, the horizontal force F in Figure 14 balances with the friction moment M, depending on the moment arm length L.

The free vibration analysis, time history earthquake analysis is performed by using SAP 2000 software, the natural and mode shapes of the building are obtained from the free vibration analysis, from the time history analysis, the time dependent dynamic responses of the building for the whole duration of the earthquake excitation, the base shear, displacement, shears, moments and axial loads of the elements at various amounts of earthquake ground motions have been determined.

The understanding of seismic behavior of building structure by isolators has been done by four analysis methods such as―(without use of seismic isolation, structure foundations of traditional) (Fix), use isolation methods (rubber and sliding isolators) (LRB + FSB), (rubber, sliding with rotation friction dampers at the base of the building) (FD + FSB + LRB) Figure 15 and Figure 16(b), and (rubber, sliding with rotation friction dampers at the ground floor level) (FD1 + FSB + LRB) Figure 16(c).

El Centro earthquake is selected for Time History analysis to understand the seismic performance of the case study building.

We will study the building several heights (eight-story, twelve-story, sixteen floors, and twenty-story).

The studied construction of reinforced concrete (Figure 16), and higher multiple floor equals 3 m, columns dimensions: 50 × 50 cm, dimensions Beams: 70 × 30 cm, Solid slab thickness 15 cm, loads of coverage: 3 KN/m², liveloads: 3 KN/m².

The required material properties like mass, weight density, modulus of elasticity shear modulus and design values of the material used can be modified as per requirements or default values can be adopted Beams and column members have been defined as “frame elements” with the appropriate dimensions and reinforcement. Soil structure interaction has not been considered. Slabs are defined as area elements having the properties of shell elements with the required thickness.

In our case, the slabs have been modeled as rigid diaphragms and in this connection, the center of rigidity (mass) and center of gravity of building is considered same in order to neglect the effect of torsion.

q T)Fixed) = 0.7 sec

q T)FSB + LRB) = 1.9 sec

q T)FD + LRB + FSB) = 0.9 sec

q T)FD1 + LRB + FSB (= 1.89 sec

Comparing the Displacements of cases isolation (Figure 17), we find:

Comparing the floor drift of the structure height 8 floors (Figure 18):

Comparing Base shear of cases isolation (Figure 19), we find:

We have the follow-up analysis of the structure of the higher (12-16-20) floor and compare the results in terms of period (Table 1), base shear (Table 1), displacements (Table 2), and drift (Table 3), and collected results in following tables:

Comparing the results of the use of hybrid isolation system (LRB + FSB) with friction damper (FD) on the base shear (Figure 20), displacements (Figure 21), and drift of the structure (Figure 22), with increasing the height of the structure and compare it with the rubber bearings isolated structure from a previous study [10] :