I have gone through your facts of the case and read your issues carefully which indicates that it has to be addressed urgently as follows.
1-The relationship between landlord and tenants are of licensors and licensees whereby licensed property is owned by landlord and used,occupied by the tenants.
2-The taxes, structural changes and major repairs are the subject matter of landlord while internal affairs and maintenance of the property is the subject matter of the tenants.
3-The commercial shops which are being used by you was closed for quite long time and after opening you found and verified through an architect that it needs structural repairs.
4-If it needs small painting work, ceiling plaster within your shop then the existing interior expenses would be taken care of the same by you. If large portions of ceiling in side of your shop is damaged and beams are cracked then it goes to the landlord and landlord has to get it repaired with prior intimations to Municipal Corporation in writing seeking permission for the repair work with architectural design and plan prepared by the authorized architect.
5- If you do not get proper reply of repairing work of structural damage of your shop then Please issue a legal notice to get the work done within a week or two and after expiry of the period you carry out the work and claim it from the landlord or adjust it while paying rent for the next period. You may have to move civil court and or small causes court which deals with the disputes of property rights, taxes,expenses and penalties between landlord and tenant.
I hope you have proper remedy with you now to proceed with proper directions and course of action.
All the best .
Best regards.