def conc_frame_yield_drift(fye, youngs_steel, av_bay_length, av_beam_depth):
    """
    Yield drift of a concrete frame from DDBD (Priestley et al. (2007)
    :param fye: Effective yeild strength of reinforcing steel
    :param youngs_steel: Young's modulus of reinforcing steel
    :param av_bay_length: Average bay length
    :param av_beam_depth: average beam depth
    :return:
    """
    return 0.5 * fye / youngs_steel * (av_bay_length / av_beam_depth)