Design any bridge — girder, slab, box girder, truss, arch, cable-stayed, suspension, integral portal or box culvert — for road, rail or pedestrian loading. Pick the type and the studio builds the whole structure as a frame model, moves the code vehicles along every influence line, finds stay pretensions and cable forces, runs second-order, modal, footbridge-comfort and seismic analysis, designs every member, sizes cables and plates automatically, shows it in 3D and prices it. For girder bridges choose the spans, deck and girder type; the studio moves the code vehicle across the bridge to build moment and shear envelopes, shares the load between girders, designs the composite steel, prestressed or RC girders, the deck slab and the bearings, checks the pier and abutment and prices the job — drag the truck, the piers and the girder spacing as you go, then take the A3 drawing set, Excel and report.
Scope & limitations
For concept, preliminary design and education. Plane-frame and line-beam models do not replace a 3D grillage or finite-element analysis, staged construction, aerodynamic studies of long spans or skewed and curved decks; detailed design must follow the governing bridge code in full and be independently checked.
What the bridge design studio does
Advanced analysis: a 3D grillage of the deck (straight, skewed or horizontally curved) with influence surfaces for every girder moment, shear, torsion and bearing reaction and the design lanes positioned across the carriageway; staged construction with creep and shrinkage (EN 1992 Annex B, step-by-step) for precast girders made continuous, steel-composite decks, falsework, span-by-span and balanced cantilever, with moment redistribution, deflection history and precamber; post-tensioning losses (friction, wobble, draw-in, elastic shortening, long-term) with primary and secondary moments; load rating (inventory, operating and a user-defined legal or permit vehicle); linear buckling of the whole bridge; modal time history for moving vehicles, high-speed train speed sweeps, walkers and earthquakes (pasted or spectrum-matched synthetic records); and pier pushover with fibre moment–curvature and displacement demand.
Nine bridge types: girder (steel composite, prestressed I or RC T-beam, 1–6 spans), slab (RC, post-tensioned solid or voided), box girder (post-tensioned concrete or steel composite, multi-cell), steel truss (Pratt, Howe, Warren, Warren with verticals; through or deck; simple or continuous), arch (tied through-arch or deck arch, two-hinged or fixed, steel or concrete rib, one or two ribs), cable-stayed (one or two towers, fan, semi-fan or harp, one or two cable planes, floating, bearing or monolithic deck, auxiliary piers), suspension (sag, hanger spacing, suspended or unsuspended side spans, hinged or continuous girder), integral portal (legs on fixed, pinned or piled foundations with earth pressure and temperature) and box culvert (one to four cells under fill on an elastic foundation). Each carries road vehicles (AS 5100 SM1600, AASHTO HL-93, BNBC/RHD, EN LM1), railway loading (EN LM71 with α and Φ2, AREMA Cooper E80) or pedestrian crowds.
Every type is analysed as a complete plane frame: permanent load, prestress by load balancing with the secondary moments, cable-stay pretensions by the zero-displacement method with Ernst modulus, suspension permanent state from statics and the linearised deflection theory, P-Δ about the permanent state, temperature, earth pressure, influence lines for every member with the vehicles and lane loads on the adverse parts, deflection envelopes, natural modes, footbridge comfort (HIVOSS) and response-spectrum seismic. Every member is designed — steel buckling and N–M, composite stresses, concrete N–M with the reinforcement chosen, prestressed stresses, strength and web shear, cables at 0.45 fpu — with automatic sizing of steel members, cables, plates and tower walls, arch in-plane buckling, bearings, joints, quantities and cost, construction method, 3D model, A3 drawings, DXF, Excel, CSV and a hand-off to the 3D Frame Studio.
Set out a girder bridge of one to three spans, simply supported or continuous, with the deck width, girder spacing and slab; drag a pier on the elevation to change the spans and drag the girder spacing on the deck section.
Analysis is a line-beam stiffness model with influence lines for moment, shear and reactions at every station. The code vehicle — AS 5100 M1600, AASHTO HL-93 truck or tandem with the lane load, or Eurocode Load Model 1 per notional lane — is moved across the bridge in both directions with variable axle spacings, the lane load is placed on the adverse parts of each line and, for continuous spans, the AASHTO two-truck case is checked for hogging. Drive the vehicle across and watch its bending moment against the envelope.
Load sharing uses the AASHTO LRFD distribution factor formulas or Courbon's rigid-deck method with lanes placed eccentrically. Girders: composite steel plate girders (plastic moment, web shear, fatigue), precast prestressed I-girders (strand count chosen automatically, transfer and service stresses, flexural strength, shear) or RC T-beams (bars, stirrups, cracked deflection), plus live-load deflection and the deck slab by the strip method.
Substructure: laminated elastomeric bearings (shape factor, compression, shear strain, stability), thermal movement and the deck joint, the pier under dead, live, braking, wind, temperature and earthquake actions with piles, and the abutment's sliding, overturning and bearing checks; quantities, cost and the construction sequence with hold points.
Outputs: an A3 drawing set (general arrangement, deck section, envelopes, girder, bearing, pier and abutment), an Excel workbook with live dead-load, distribution, combination, section, prestress, bearing and abutment formulas, and JSON.