  We study the manipulation of quantum entanglement by periodic external
fields. As an entanglement measure we compute numerically the concurrence of
two flux qubits coupled inductively and/or capacitively, both driven by a dc+ac
magnetic flux. Also we find an analytical lower bound for the concurrence,
where the dominant terms correspond to the concurrence in the Floquet states.
  We show that it is possible to create or destroy entanglement in a controlled
way by tuning the system at or near multiphoton resonances. We find that when
the driving term of the Hamiltonian does not commute with the qubit-qubit
interaction term, the control of the entanglement induced by the driving field
is more robust in parameter space. This implies that capacitively coupled two
flux qubits are more convenient for controlling entanglement through ac driving
fluxes.
