Bridge piers, pile caps, and deck cages routinely specify 32-40 mm deformed bars, which pushes the rebar bender selection past the 25 mm comfort zone of masonry and light-landscape work and into the 32-50 mm heavy-civil band [S1]. A portable 10-25 mm unit that handles rebar for retaining walls cannot bend the 36 mm longitudinal bars in a typical highway overpass bent without stalling, overheating, or producing out-of-tolerance bend angles [S3].
Selection for a bridge project therefore collapses to four spec gates, in this order: maximum bar diameter on the bending schedule, electric versus hydraulic drive power source, programmable bend-angle range (0-180 degrees), and minimum inside bend radius to satisfy ACI 318 / AASHTO LRFD rebar detailing. Bridge detailing under U.S. practice typically uses 6db (six bar diameters) for stirrups and 4db for standard hooks, and any candidate bender must produce those radii without flat-spotting the bar.
Capacity Bands and Where Each One Fits a Bridge Drawing
Three capacity tiers dominate bridge rebar work: 10-25 mm for light landscape and small footings, 10-32 mm for general pier and cap cages, and 10-42 mm (or 10-50 mm) for heavy main-bar bending on long-span decks and large-diameter caisson cages [S1]. A bender with a 10-32 mm rating handles 90 percent of the stirrups, ties, and smaller longitudinal bars in a typical 20-30 m span bridge, while a 10-42 mm unit is required whenever the schedule calls out 36 mm or 40 mm main reinforcement [S1][S3].
The TYB-HD42D-class electric bender, rated 10-42 mm and stocked in regional warehouses with full spare-parts support, is the most common heavy-civil specification seen on Southeast Asian bridge tenders as of 2026 [S1]. For comparison, portable 10-25 mm units remain the default for masonry rebar work and are documented in a separate selection guide on rebar bender selection for masonry, while tunnel segment cages have their own radius-and-repeatability profile covered in rebar bender selection for tunnel segment cages.
Drive Type, Motor Power, and Productivity on Site
Three-phase electric (380-415 V) hydraulic-drive benders in the 2.2-4.0 kW band are the default for stationary shop work where a 32-42 mm bar is processed at high cycle rates, and suppliers such as PROSPER Hangzhou list CNC-integrated electric-hydraulic bender/cutter combinations in this power class [S3]. Single-phase 220 V units in the 1.5-2.2 kW range are typical for portable site work up to 25-32 mm but stall on sustained 36 mm production. The rebar bender selection for landscaping guide covers the lower end of that portable envelope, including the cordless electric demolition-tool platform that some crews use for small-diameter bending on remote sites [S3].
For bridge cages, a useful first-pass gate is: motor power in kW should be at least 0.10-0.12 kW per millimeter of rated bar diameter, so a 36 mm machine lands near 3.6-4.3 kW and a 42 mm unit near 4.2-5.0 kW. Benders below that ratio typically slow cycle time below 5 seconds per 90-degree bend on the top diameter, which destroys productivity on a 50-ton cage.
Bend-Angle Range, Mandrel Geometry, and ACI 318 / AASHTO Compatibility
Bridge stirrups need 90- and 135-degree hooks, seismic hooks require 135 or 180 degrees, and cap-beam bar splices often need 180-degree hooks around corner bars, so a programmable 0-180 degree range with 1-degree increments is the minimum spec for bridge work. Inside bend radius must be settable to 2db, 3db, 4db, and 6db, because ACI 318 Chapter 25 and the AASHTO LRFD Bridge Design Specification tie allowable mandrel diameter to bar size, grade, and seismic category. A bender whose mandrel is fixed or limited to a single radius cannot meet those gates without field re-mandrelling, which is a documented quality risk on bridge pours. [S1]
Two-axis (dual-direction) bending heads are now standard on CNC steel-bar bender/cutter integrated machines from Chinese OEM/ODM suppliers, and they are listed alongside single-direction portable units in the same product catalog [S3]. For bridge work, the dual-direction head removes the manual flip step that causes the most angle-tolerance failures on 135-degree seismic hooks.
Throughput, Power Source, and Site Logistics
Bridge cages are tonnage games. A single pier cage can require 8-15 tons of bent rebar, and a deck slab another 20-40 tons per span, so the bender must sustain 200-400 bends per 8-hour shift without overheating. Continuous-duty hydraulic units with oil-cooling hit that rate; intermittent-duty gear-driven units typically do not above 32 mm. [S1]
Generator pairing is a real constraint: a 36 mm electric-hydraulic bender at 4 kW plus a 36 mm electric shear at 3-4 kW needs a 15-20 kVA genset with voltage regulation, otherwise motor contactors drop out on each bend stroke. Bridge site electricians routinely spec a 25 kVA unit as a 30 percent margin, which is consistent with what crews document in the construction tools power-planning notes.
Spare-Parts, Lead Time, and After-Sale Gates
Bridge schedules run on critical-path tower cranes and deck pours, and a bent-bar machine down for 3-5 days will halt a cage crew of 12-20 ironworkers, so spare-parts availability inside the same country is a procurement gate, not a nice-to-have. Distributors that hold a full spare-parts inventory for every model they sell, and that publish on-site plus warehouse-based repair options, shorten that downtime risk [S1]. Peak-season lead time for CNC integrated bender/cutter lines out of East China was 1-3 months as of 2024 supplier disclosures, and 15 workdays off-season, with FOB, CIF, and DDP Incoterms available [S3].
For a bridge tender in 2026, hard-ask the vendor three things: country-stock spare-parts list, guaranteed on-site response in hours, and a loaner-unit clause for any failure longer than 48 hours. A rebar cutter that shares the same hydraulic pack, mandrel pins, and control PCB as the bender halves the spare-parts inventory you carry, which is a quiet but real logistics win on remote bridge sites.
Comparison of Bender Tiers Against Bridge Spec Gates
Against the four main bridge gates, the three capacity tiers line up as follows. Portable 10-25 mm electric, 1.5-2.2 kW, single-phase: passes on small footings and approach slabs, fails on 32 mm+ main bars and on continuous-duty 200-bend shifts. Mid-range 10-32 mm electric-hydraulic, 2.2-3.0 kW, 3-phase: passes on most pier and cap cages, marginal on 36 mm main bars, passes on bend-angle range. Heavy 10-42 mm electric-hydraulic, 3.5-5.0 kW, 3-phase with CNC option: passes on every bridge spec gate including 36-40 mm main bars and 180-degree hooks, at the cost of weight and a 15-20 kVA genset. [S2]
Bridge rebar detailers should also note that any rebar coupler mechanical splice on the drawing shifts the bending tolerance to the coupler manufacturer's spec (typically +/- 2 degrees at the bend plane), which is tighter than a plain-hook bend and pushes the selection toward CNC-controlled two-axis heads [S3]. Where a rebar bender selection has to coexist with rebar grade 60 (420 MPa) versus grade 80 (550 MPa) input, confirm the bender's tonnage rating at the higher grade, because 80-grade bar needs roughly 30 percent more bending force at the same diameter.
Trackable next signals for bridge procurement teams: updated AASHTO LRFD rebar detailing tables for grade 80 main reinforcement (pending as of mid-2026), and any 2026 revision to ACI 318-25 Chapter 25 mandrel-diameter provisions. Until those publish, the conservative bridge spec is a 10-42 mm electric-hydraulic bender, 3.5-5.0 kW, 0-180 degree CNC, dual-direction head, and a country-stocked spare-parts contract with a 48-hour on-site response.