Smith, 29, is serving a 12-month ban from international and domestic Australian cricket as a result of his involvement in the ball-tampering scandal during the Test series against South Africa in March.
The batsman has featured in the Global T20 Canada competition since being suspended by Cricket Australia and he will resume his career when the Tridents face the Guyana Amazon Warriors on August 12.
Tridents coach Robin Singh said: “It is a huge blow to lose Shakib for the tournament but in Steve Smith we have a truly world-class replacement who can help to bring power to our batting line-up.
“As a man who has played cricket at the highest level all over the world we are very confident that Smith will be a big success with the Tridents.”
No reasons were given for Bangladesh international Shakib’s withdrawal from contention for Barbados.
In late March, then-Australia skipper Smith and his vice-captain David Warner were stripped of their positions and handed one-year bans after opening batsman Cameron Bancroft attempted to alter the condition of the ball with home-made sandpaper against South Africa in Cape Town.
Bancroft, 25, was banned for nine months and coach Darren Lehmann stepped down over the incident.
India off spinner Ravichandran Ashwin has decided to stay a little longer in England after completing the eagerly anticipated Test series.
The 31-year-old will re-join Worcestershire for their final two County Championship games in 2018 after a successful spell at New Road last season.
Ashwin, who has arrived in England to take part in India’s warm-up match against Essex at Chelmsford from Wednesday, is likely to start as India’s lead spinner for the five-Test series, while his four hundreds should see him contributing with the bat
Last season, Ashwin had a major impact at Worcestershire, taking 20 wickets in four matches while averaging 42.50 with the bat.
“We are delighted to have Ashwin coming back for what could be a key part of the season,” said Worcestershire’s chief executive, Matt Rawnsley.
“He is one of the best spinners in world cricket and the influence he had when here last season cannot be underestimated.
“The lads all speak so highly of him, the impact he had on the field and the way he slotted in so well off the pitch and he was willing to offer advice to our young spinners like Ben Twohig.”
Most Test wickets post Muralidharan...— Mohandas Menon (@mohanstatsman) July 23, 2018
375 @ 55 b/w - James Anderson (90 Tests)
359 @ 57 b/w - Rangana Herath (70)
334 @ 56 b/w - Stuart Broad (90)
316 @ 53 b/w - R Ashwin (58)
306 @ 63 b/w - Nathan Lyon (78)
b/w - balls per wicket#SLvSA
The two matches Ashwin will feature in are Worcestershire’s trip to Essex, starting on September 18, and the home game against Yorkshire the following week.
The Worcester-based side currently sit bottom of Division One, and need reinforcements as they seek to avoid being relegated back to Division Two for the third time in ten years.
“Ashwin is world class and he loved it at Worcestershire,” added head coach Kevin Sharp.
“Conversations have been ongoing about him coming back and I’m sure he will be a great fillip for us.
“He had a massive input for us on and off the field last summer in helping us gain promotion and he is a high class individual.”
Unfortunately Virat Kohli had to pull out of a stint with Surrey due to injury, but several other India stars have enjoyed spells in county cricket this summer.
Cheteshwar Pujara played the first half of the season for Yorkshire, while Ishant Sharma and Varun Aaron played for Sussex and Leicestershire respectively, and Axar Patel has signed for a spell at Durham.
Bhuvneshwar is ruled out of the first three Tests after aggravating his back in the third ODI defeat to England last week while Bumrah will not be available for the first Test following surgery on his thumb injury aggravated in the Ireland T20 series.
But Zaheer insists India have sufficient bench strength to make up for their absences with Mohammed Shami, Umesh Yadav and Shardul Thakur included in the squad.
“Bumrah is injured for the first few matches and there has been an injury concern to Bhuvneshwar Kumar, which is a concern seeing the forthcoming season, but I believe even after their injuries, the five-match tournament is a long series,” Zaheer said.
“I believe whichever bowlers will play – like Umesh (Yadav) is doing well, Ishant (Sharma) is a senior bowler and has to take more lead (role) and Mohammed Shami has a good record – I believe their (Bhuvi and Bumrah’s) absence will be felt, but still India’s bench strength is very strong.”
Indian legend Sachin Tendulkar has already spoken that the bowling attack is the most complete and Zaheer agrees with the ex-batsmen.
“Yes absolutely. If you see the style, with the style of each bowler, you can say it is an accomplished attack because in different conditions, different bowlers impress more,” added Zaheer, who took 311 Test wickets.