The phrase "to join the strike" means to participate or become a part of a protest or work stoppage where workers collectively refuse to work, typically to demand better conditions or rights from employers. Full definition
Teachers, firefighters and council workers joined the strike, which follows disputes with the government over pay, pensions and cuts. (bbc.co.uk)
Meanwhile, the Nigeria Labour Congress, NLC has begun notifying workers both in government and private owned organizations to be prepare in joining the strike action on Wednesday. (nigeriapoliticsonline.com)
A week or two ago we were talking about an agreed fee with Juventus for Vidal, 3 weeks prior to that we were talking about Martinez joining the strike force. (justarsenal.com)