Beam design workspace วิเคราะห์และตรวจสอบคาน
3D beam / แบบจำลองคาน
Change the dimensions here or tap a dimension label on the model. Geometry and calculations update together.
Beam reinforcement designer
เว้น cover จากผิวคอนกรีตถึงผิวเหล็กที่ปลายคานทั้งสอง · งอขอตามภาพอ้างอิง D ด้านใน = 6db สำหรับ DB10–25 · รูปขอและหางขอต้องอยู่ภายในคานและไม่ล้ำแนว cover. Hook shapes are schematic; bar clashes and anchorage require separate detailing.
Strength envelope / ชุดแรงออกแบบ: all 19 supplied photo combinations · 1–3 layers per face · 2-legged stirrups
Selected main bars / เหล็กหลักที่เลือก
Automatic selectionCount is the total at a full section. With 2–3 layers, you can shorten the existing innermost row below while the outer rows stay continuous between end covers. จำนวนเหล็กรวมในหน้าตัด · เลือก 2–3 ชั้นแล้วลดความยาวชั้นในเดิมได้ด้านล่าง
Stirrup zones / เหล็กปลอกแบ่งช่วง
Zone lengths are measured along the analysis span. Auto spacing follows each zone's peak shear.
Shorten the existing inner layer ลดความยาวเหล็กชั้นในเดิม
Retain the existing inner row only where the moment needs it. Its count, diameter and layer position stay tied to the selected bars above. For 4 bars in 2 layers: 2 outer bars stay continuous, and the same 2 inner bars receive shorter lengths. เหล็ก 4 เส้น 2 ชั้น → ชั้นนอก 2 เส้นต่อเนื่อง + ชั้นในเดิม 2 เส้นเฉพาะช่วง
Checks along each range / ตรวจแต่ละช่วงและปลายเหล็ก
Ranges and saved steel are preliminary geometry estimates. Full bar strength is assumed within each entered range; development and anchorage are not checked. Extend and detail each bar with an engineer before construction. ช่วงที่เลือกยังไม่รวมการออกแบบระยะฝังยึด ระยะต่อทาบ และเงื่อนไขการตัดเหล็ก
Selected layout checks / ตรวจสอบแบบที่เลือก
Analysis-span schematic · selected ACI 318-19 checks only. Both faces are checked when sagging and hogging occur; compression strength is not credited. Anchorage, hooks, laps, seismic confinement and serviceability are not designed here. ยังไม่ใช่แบบพร้อมก่อสร้าง.
Load & support model
SERVICE · D + LForce & displacement diagrams
x measured from AShear forceแรงเฉือน
Bending momentโมเมนต์ดัด
Elastic deflectionการโก่งตัวเชิงยืดหยุ่น
Engineering workspace
Automatic sizing utilization
Load-case comparison / กรณีน้ำหนักบรรทุก
Immediate elastic deflection is shown for each case. Strength design uses the envelope; serviceability compares service loads.
Deflection reference / การโก่งตัว
A reference comparison, not a code pass/fail. Uses your E and effective-I multiplier. Cracking, creep, shrinkage, load duration and finishes are not modelled.
Compare SD40 / SD50 and bar sizes
Same beam, loads, cover, aggregate and stirrup strength. Each row selects its minimum viable bar count. Choosing Use updates the main recommendation.
Steel quantity estimate / ประมาณปริมาณเหล็ก
For estimating only. Main lengths follow the selected path inside end cover, including chosen main arcs and tails. Development, laps, support extensions, stirrup hooks and fabrication allowances are excluded. This is not a bar bending schedule or purchase list.
Section results / ผลตามตำแหน่ง
21 regular stations plus all point-load locations. V− and V+ show both sides of a shear jump. Values follow the selected diagram load case and force units.
Bar weights & selected quantities
Nominal area and mass at 7,850 kg/m³. Factory stock: SD40 DB10, DB12, DB16, DB20, DB25; SD50 DB16, DB20. Stock bars are 12 m long. Equal diameters have the same theoretical mass for SD40 and SD50; grade changes strength.
Current detailed layout / ปริมาณแบบที่เลือก
Both top and bottom bars are counted. Stirrup counts use the placed zone positions; shared boundaries count once. Main-bar lengths include the chosen end arcs and tails within cover. Centreline stirrup rectangles exclude stirrup hooks and bend allowances; anchorage, support extensions, laps and waste are excluded. Estimate only; not a fabrication or purchase schedule.
Grades & reference table / เกรดและตารางอ้างอิง
RB table sizes: 6, 9, 12, 15, 19 and 25 mm, matching the supplied SR24 reference. Factory DB stock: SD40 10, 12, 16, 20, 25 mm; SD50 16, 20 mm, all 12 m long. The DB catalogue follows the supplied factory-stock image. Nominal masses are calculated consistently from diameter and density. Available design grades remain SD40 and SD50, with entered strengths 4,000 and 5,000 kgf/cm². Round-bar mass data does not certify a stirrup grade or its suitability under the selected design equations.
Calculation details
- Total applied load
- Combined uniform load
- Gross section I = bh³/12
- Effective flexural rigidity EI
- Equilibrium residual · ΣF / ΣM
Analysis assumptions
One to eight connected spans, independent section and constant E and I within each span, vertical loads and ideal supports. Continuous beams use the direct stiffness method with exact load recovery within each span. Elastic deflection uses Euler–Bernoulli beam theory and superposition.
Rebar recommendations use selected ACI 318-19 strength equations for a normal-weight, slender rectangular beam with 1–3 tension layers and no axial load or torsion. ยังไม่ใช่แบบเหล็กเสริมพร้อมก่อสร้าง.
Equations & references
Simply supported: RB = (wL²/2 + ΣPa)/L, RA = wL + ΣP − RB.
Cantilever: RA = wL + ΣP; M(0) = −(wL²/2 + ΣPa).
V(x) = RA − wx − ΣP for loads before x.
M(x) = M(0) + RAx − wx²/2 − ΣP⟨x−a⟩.
For a continuous beam, assemble Kd = F across shared displacement and rotation DOFs. Recover V, M and deflection within each span; interior support reactions create shear jumps. No internal hinges or settlement are modelled. For one span, integrate EI y″ = M; δ = −y with the selected boundary conditions.
1 kgf = 9.80665 N. The reference screenshot’s kg/m loads are interpreted as kgf/m.
MIT · Deflections due to bending
NPTEL · Direct stiffness method for beams
NIST · Force unit conversions
ACI · Shear design provisions
ACI · Flexural design and strain limits