For each work item there could be up to 20 different disciplines
The above describes a one-to-many relationship.
What I am not clear on is whether a project can have many work items? Can it? If so, then this would be the structure
tblProjects
-pkProjectID primary key, autonumber
-txtProjectNumber
-txtProjectName
tblProjectWorkItems
-pkProjWIID primary key, autonumber
-fkProjectID foreign key to tblProjects
-txtWorkItemNumber
Since a work item has many disciplines that describes a one-to-many relationship as already mentioned above. So that table would look like this:
tblProjectWorkItemDisciplines
-pkProjWIDiscID primary key, autonumber
-fkProjWIID foreign key to tblProjectWorkItems
-txtDiscipline
But...
If a discipline can also apply to many work items that describes another one-to-many relationship. When you have 2 one-to-many relationships between the same two entities (work items & disciplines in this case), you have a many-to-many relationship which requires a junction table. If this is indeed applicable to your application (a guess on my part), you need a table to hold the disciplines and you would make tblProjectWorkItemDisciplines your junction table. That would look like this:
tblDisciplines
-pkDiscID primary key, autonumber
-txtDiscipline
tblProjectWorkItemDisciplines
-pkProjWIDiscID primary key, autonumber
-fkProjWIID foreign key to tblProjectWorkItems
-fkDiscID foreign key to tblDisciplines
For the bidders, it would be best to hold the basic company info in a table
tblCompany
-pkCompanyID primary key, autonumber
-txtCompanyName
-txtAddress
You said that you can have many bidders on a particular discipline. I must also assume that a bidder can bid on more than one discipline. This again describes a many-to-many relationship, so we need another junction table
tblBidderProjectWorkItemDisciplines
-pkBidderPWIDiscID primary key, autonumber
-fkCompanyID foreign key to tblCompany
-fkProjWIDiscID foreign key to tblProjectWorkItemDisciplines
-currBidAmount
-spAwardPercent
You can use the spAwardPercent (single precision number field) to indicate the percentage (as a fraction) of the particular discipline that goes to a particular bidder. i.e. 0.50 (50% to bidder 1) and 0.50 to bidder 2 for a total of 1.00 (100%).