Parallel spring

Some materials demonstrate anelastic behavior and this is often modeled by a spring in series with a parallel spring and dashpot unit (standard linear solid, SLS). 

By inspection of Figure 4.14(a) we see the first term of eqn 4.50 to be the time-independent deflection of the spring the second term is the time-dependent deflection of the parallel-spring dashpot element. 

In Fig. 2.20, two masses and three parallel spring-damper arrangements are connected through a lever. Inertia of the lever is neglected. The lever is assumed to be long enough, so that the endpoints approximately translate in the i and V2 directions. A step input force F is applied to the mass m. The goal is to predict displacements xi and X2-... 

In the above equations, ht is the beam depth and hcs is the overall slab thickness including the depth of the steel deck, but the model assumes that the interaction between the slab and the column only occurs over the slab thickness above the steel deck, hds, to represent actual test conditions. The parameter, tbf, is the beam flange thickness. For components 1 and 5, the deformation varies among the series of n parallel springs used over the slab thickness. For the concrete in compression (Component 1), a distinctimi is also made between unconfined (5i5) and confined (8i i) concrete fibers. Unconfined concrete cmidition is assumed above the slab reinforcing steel (of thickness hds,nc in Fig. 13b), and therefore, the parameters Ac and A c correspond to the... 

When these restraint settings are generalized (for any simulator) into one linear net restraint (and not two parallel springs), and when the leverage issue is corrected for, the desired net stiffness values recommended for soft tissue restraint are as detailed in Table 26.1. These generalized settings have been proposed as part of a major revision of the force-control ISO standard 14243-1 [38]. 

Fig. 11.13. Parallel glass spring for microforce measurements scaiming electron micrograph showing in detail a deformation bar (left) of a parallel spring, and the design of another parallel spring is shown on the right...

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