What a Bolt List Contains
- Bolt diameter — 3/4", 7/8", 1", 1-1/8"
- Bolt grade — A325 (F1852 TC), A490, A307
- Bolt length — in 1/4" increments; determined by grip length (total material thickness) plus thread engagement
- Installation method — bearing (N or X) or slip-critical (SC); affects nut and washer requirements
- Quantity — shop bolts (installed in the shop) and field bolts (installed during erection) listed separately
- Nut and washer requirements — hardened washers required under bolt head and nut for pretensioned and SC installations
- Special requirements — galvanized bolts, stainless, or oversized holes
How Bolt Lists Are Generated from Tekla
Tekla generates bolt lists from the model's bolt objects. Every bolt in every connection — shop and field — is an object in the Tekla database with defined diameter, grade, length, and installation method. The bolt list report extracts all bolt objects and summarizes by type and length. Accuracy depends on the connection models: connections built using Tekla's parametric connection components have correctly assigned bolt objects; custom connections built with generic geometry may have incomplete or incorrectly attributed bolt objects.
Common Bolt List Errors
- Bolt length calculated from model thickness not matching actual grip length in field assembly
- Field bolts and shop bolts combined in a single quantity (they should be tracked separately)
- Grade confusion between A325 and F1852 TC bolts (functionally equivalent but ordering must match the project spec)
- Missing washers for hardened-washer-required installations
- Galvanized bolt quantities not separated from standard bolt quantities
Bolt Length Calculation in Practice
Bolt length is the most frequently miscalculated variable in a bolt list. The correct bolt length equals the total grip (sum of all material thicknesses through which the bolt passes) plus the thread engagement required for the nut, plus the washer stack thickness if hardened washers are specified. AISC Design Guide 2 provides standard grip-to-length tables for common bolt sizes. In Tekla, bolt lengths are assigned by the connection component based on the modeled material thickness — but the model must include all washers as objects (not just notes) for Tekla to calculate the correct length. Connection components built without washer objects will produce bolt lengths that are short by one or two increments, meaning nuts cannot be fully engaged.
RCSC Specification Requirements for Bolt Lists
The Research Council on Structural Connections (RCSC) Specification for Structural Joints Using High-Strength Bolts governs the installation requirements for A325 and A490 bolts and must be understood when generating bolt lists. RCSC requires: hardened washers under the bolt head and nut for direct tension indicator (DTI) installation; beveled washers where bolt bearing surface is not perpendicular to the bolt axis; and oversized-hole washers for connections with oversized holes. Each of these requirements affects the bolt list's washer quantities and bolt length calculations. A bolt list that does not account for RCSC washer requirements will be short on washers and may produce bolt lengths that do not accommodate the washer stack.
Anchor Rod Lists as a Component of the Hardware Package
Anchor rods — the cast-in-place threaded rods that connect column base plates to foundations — are frequently omitted from bolt lists because they are installed by the concrete contractor, not the steel fabricator. However, the steel detailer is responsible for producing the anchor bolt plan and specifying anchor rod dimensions, grades, thread lengths, nut sizes, and washer sizes. ASTM F1554 is the governing standard for anchor rods — Grade 36, 55, and 105 are the common options. Grade 105 is weldable but must be specified by the EOR. The anchor rod list should appear as a separate section of the hardware package, clearly distinguishing between rods supplied with the steel (for embedded plate assemblies) and rods supplied to the concrete contractor for cast-in-place installation.
Validating the Bolt List Before Purchasing
Before any bolt order is placed, the bolt list should be verified against the model's connection component inventory. Run a Tekla report that lists the bolt count by connection component type — shear tab connections, moment end plate connections, brace gusset connections — and compare the subtotals to the overall bolt list. If the subtotals do not sum to the total, a connection type is missing from the report or a bolt was assigned to the wrong component. Additionally, confirm that the bolt specification (grade, installation method, any galvanizing requirement) matches the project spec for every bolt type on the list. Purchasing a project's worth of A325-N bolts when the spec requires A490-SC is a costly error that a 30-minute pre-purchase verification would prevent.