# Coupling Beam and Coupled Shearwall Modelling

**4.5.4.1 -** Reinforced concrete *bond beam (hollow) walls* are vertical structural system elements in which two *hollow* curtain parts are connected with tie beams with short and very high shear strengths and work together *as a single curtain* . Thanks to strong tie beams, these types of curtains show a behavior between curtains without gaps and frames (See **4.5.4.5** ).

**4.5.4.2 - The **cross-sectional shapes of the curtain parts forming the **tie-** beam curtain can be rectangular or generally U or C-shaped like building cores ( **Figure 4.1** ).

**4.5.4.3 - The** base tipping moment of the bond beam (hollow) **wall** is calculated by **Equation (4.13)** :

Here, the total tipping moment at the base of the wall with *M *_{DEV} bond beam (hollow), the bending moments obtained at the base due to the earthquake effect in the curtain parts forming the wall with *M *_{1} and *M *_{2} bond beams, and *N *_{V} as the sum of the shear forces in the bond beams under *the* earthquake effect, It corresponds to equal tensile and pressure axial forces formed at the base of the curtain parts. *c* shows the distance between the cross-section gravity centers of the curtain parts ( **Figure 4.1** ). The magnitude obtained from **Equation (4.13)** is **4.3.4.5** and**In 4.3.4.6** , the curtain *base overturning moment will* be used as *M *_{DEV} .

**4.5.4.4 -** The *bond degree coefficient *_{Ω} , which is taken as basis in the definition of bond beam (hollow) walls, is given in **Equation (4.14)** .

**4.5.4.5 - ***Bond beam (hollow) screen* , **Eq. (4.14)** 'in the *bond order coefficient* ' s **in Eq. (4.15)** 't provides condition according to defined as the structural element:

**If the** condition defined in **Equation (4.15) is** not fulfilled, each part of the *curtain is* deemed to be a curtain *without gap* . In addition to this condition, in order to prevent the occurrence of excessive axial forces in the curtain parts, the condition ≤ 2 3 **/** should be tried to be fulfilled.

**4.5.4.6 - The** curtain parts forming the reinforced concrete tie-beam curtain **shall** be modeled according to **4.5.3.7** or **4.5.3.8** .

**4.5.4.7 -** Tie beams can be modeled as frame members. The *effective section stiffness of ***tie** beams *will* be determined according to **4.5.8** .