The web plate is a central component in steel and composite construction. As a vertical or inclined plate, it connects the flanges of a beam, transfers shear force, and stabilizes the overall geometry. In practice, it appears in hall girders, bridges, crane runway girders, box girders, composite beams with a concrete slab, as well as a stiffener in tanks and shafts. For concrete demolition and special deconstruction, understanding the configuration and load-bearing behavior of the web plate is important in order to cut selectively, expose, or safely neutralize load paths—for example, during the selective deconstruction of composite cross-sections, in which concrete zones are carefully removed using a concrete pulverizer and stone splitter and concrete splitter.
Definition: What is meant by web plate
The web plate (also: web, web plate) is generally the thinner plate component of a beam that connects the flange plates (top flange, bottom flange). The web plate predominantly carries shear force, helps limit eccentricity, and stabilizes the flanges against buckling. In welded plate girders and box girders, the web plate is cut from rolled plate and welded to the flanges. In composite structures, the web plate works together with concrete components (e.g., cast-in-place concrete concrete slab) via shear connectors, and it also plays a role as a separation plane during deconstruction.
Design variants and typical geometries of web plates
Web plates occur as a single web in an I-girder, as a double web in box girders, or as stiffening plates in tanks and shafts. Key parameters are web thickness tw, web height hw, web openings (penetrations), beads, and edge radii. The geometry influences buckling resistance, shear capacity, and processability during deconstruction.
Configuration, terminology, and structural action
The structural behavior of a beam is significantly determined by the web plate. While flanges primarily resist bending moments, the web transfers the shear force. At high shear stresses, web buckling can occur; stiffening angles or plates then increase stability. Web openings facilitate installations but must be reinforced all around. In composite beams, the web plate transfers shear forces between steel and concrete; during deconstruction these composite zones must be deliberately released.
Materials, standards, and quality
Unalloyed or low-alloy structural steels (e.g., S235, S355) according to applicable European standards are common. Execution follows recognized rules of practice for steel construction and composite construction. In service, corrosion, fatigue due to cyclic loading, and local effects (e.g., crane impacts) act on the web plate. Clean weld seams, correct edge finishing, and adequate corrosion protection are decisive for durability.
Fabrication and joining techniques
Web plates are cut from plate sheets (thermal or mechanical), aligned, and welded to flanges. Stiffeners are welded on or bolted. Minimum spacings and edge radii apply to web openings to avoid stress concentrations. For subsequent work in existing structures, low-emission and low-vibration methods are advantageous. In deconstruction, concrete zones around composite areas can be released with a concrete pulverizer and separated with stone splitter and concrete splitter with low stress before the web plate is separated as a steel component.
Typical fields of application of web plates
Web plates are found in:
- welded plate girders and box girders in hall and bridge construction
- crane runway girders and overhead cranes with high fatigue loading
- composite beams with cast-in-place concrete slabs and precast elements
- steel frames, column heads, and end-plate connections with web stiffeners
- tanks, silos, and large-format shafts as stiffening plates
- special structures in tunnel construction and temporary auxiliary girders
Deconstruction and processing: procedures on web plates
In concrete demolition and special demolition, a planned approach is essential: define loads, provide shoring, deliberately release the composite, cut the steel, and cleanly separate materials. In composite beams, exposing the web plate facilitates subsequent steel cutting. A concrete pulverizer is suitable for gentle removal of concrete cover, while stone splitter and concrete splitter create controlled separation cracks (e.g., using hydraulic rock and concrete splitters). In addition, selective concrete crushers can be used depending on the work concept and boundary conditions.
Selective deconstruction of composite beams: exemplary sequence
- Review existing documents; identify web thickness, stiffeners, and composite connectors.
- Temporary securing and load redistribution; define separation cuts.
- Remove concrete layers in the area of the web plate with a concrete pulverizer; produce relieving relief cuts using stone splitter and concrete splitter.
- Expose composite interfaces and carefully release connection details.
- Cut the exposed web plate along the specified cut lines; separate steel and concrete by type.
Openings, stiffeners, and details on the web plate
Web openings (e.g., for service penetrations) alter shear flow and web stiffness. Perimeter frames or tabs distribute stresses. Transverse and longitudinal stiffeners prevent web buckling in slender webs. In deconstruction these details are relevant because they determine cut paths, tool access, and the sequence of separation work, and they can redirect point loads.
Damage, repair, and assessment in existing structures
Typical damage patterns include edge corrosion loss, thinning of web thickness, cracking at weld seams, buckling waves between stiffeners, and notches at openings. Repair may include reinforcement plates, welded-on tabs, or replacement sections. Critical for deconstruction are material separation, minimizing sparks and vibration, and the safe handling of residual stresses that may be stored in the web plate.
Occupational safety and organizational notes
Measures for structural stability, dust and noise reduction, fire protection during hot work, and clear interface coordination are essential. Work on load-bearing web plates is carried out only after appropriate securing. Legal requirements can vary by project; applicable regulations and approvals must always be observed without replacing case-by-case decisions.
Sustainability, dismantling, and recycling
Single-grade separation increases the recycling rate. Steel from web plates is readily recyclable, and concrete can be processed as recycled aggregate. Using low-vibration methods—such as splitting instead of large-area percussive work—reduces emissions, protects adjacent components, and improves material quality for reuse.
Planning, documentation, and quality assurance
Before starting, geometry, material properties, stiffeners, and potential composite zones should be documented. During execution, clear cut and work points, measurement logs, and continuous stability checks are helpful. Finally, photo-based evidence and material flow records support transparent documentation.