A steel skeleton forms the load-bearing framework of many industrial, commercial, and high-rise buildings. It enables large spans, flexible floor plans, and fast assembly. In everyday construction practice, steel skeletons are relevant not only for new builds: especially during conversion, refurbishment work, interior demolition, and selective deconstruction, the safe separation of steel and concrete components plays a central role. This is where material-appropriate methods and hydraulic tools from Darda GmbH come into play, such as concrete demolition shear or hydraulic splitter, which operate with low vibration levels.
Definition: What is meant by steel skeleton
A steel skeleton is a skeletal structural system made of vertical columns and horizontal beams that together transfer loads from self-weight, use, and wind into the foundation. Overall stiffness is provided by frame action, bracing, or core zones. In contrast to massive wall–slab systems, in a steel skeleton the columns and beams primarily carry the loads; partitions and façades are non-load-bearing and can be modified or replaced. Steel skeletons are often combined with composite slabs (e.g., steel deck with cast-in-place concrete) or with masonry or concrete infill.
Construction principle and typical components
Steel skeleton constructions consist of hot-rolled I/H steel section, hollow sections, welded plate constructions, or bolted systems. Load-bearing joints are bolted, welded (via weld seam), or—on older structures—riveted. Floor systems range from jack-arch slabs between I-beams to composite slabs and steel beams with an on-site concrete topping. Steel beams are often equipped with fire protection claddings or grouted into concrete, which must be considered during deconstruction.
Frames, bracing, and joints
Frame joints govern stiffness, braces (X-, K-, or V-forms) increase bracing. Connection types influence the dismantling method: bolted connections can be loosened or cut, weld seams are separated, rivets require shearing or pressing out. The choice of method depends on cross-section, accessibility, and boundary conditions such as noise emission and vibration limits.
Composite slabs and enclosures
Composite slabs couple steel beams and concrete slab via shear connectors. During refurbishment or deconstruction, concrete portions are often removed first, then steel parts are separated. Here, concrete demolition shear are suitable for controlled fragmentation and hydraulic rock and concrete splitters for crack-controlled splitting, before steel shears for structural steel release steel profiles.
Existing buildings, refurbishment, and strengthening in steel-skeleton construction
Measured interventions are required in existing buildings: strengthening (e.g., welding on plates), replacement of individual beams, concrete topping to increase load-bearing capacity, or renewal of corrosion and fire protection. A thorough survey beforehand is necessary to identify construction era, connections, coatings, and any hazardous substance. Interventions should preserve load paths and include temporary shoring.
Existing-condition survey and documentation
Drawings, probes, and material testing provide clarity on profile types, connection means, concrete thicknesses, and built-in components. Hidden encasements (e.g., mortar, fireproofing plaster, gypsum fiber) affect the choice of dismantling method. Seamless documentation simplifies planning of cut sequences and coordination with occupational safety and disposal.
Consider corrosion and fire protection
Steel loses load-bearing capacity with increasing temperature, hence fire protection measures (claddings, coatings, concrete encasements) are common. These layers must be removed in a material-appropriate manner during interventions. Corrosion protection systems (e.g., coatings) must be treated with low emissions; the approach follows local requirements and should always consider noise reduction measures and dust suppression.
Deconstruction of steel-skeleton structures
Selective deconstruction follows the principle “from non-load-bearing to load-bearing” and “from outside to inside.” The goal is safe, low-vibration separation with high material purity through consistent demolition separation. Hydraulic tools from Darda GmbH are powered by dedicated hydraulic power units and allow controlled cuts and breaks without area-wide vibration.
- Interior demolition: removal of non-load-bearing components, utilities, and installations.
- Exposure of joints and beam flanges; removal of protective claddings.
- Section-by-section removal of composite concrete with concrete demolition shear.
- Crack-controlled splitting of massive concrete zones with hydraulic splitter.
- Separation of steel profiles with steel shear or hydraulic shear; for thick plate components, use a cutting torch.
- Orderly lowering/removal with lifting device; demolition separation and transport logistics.
Tools in selective deconstruction
The choice of tools depends on component type and boundary conditions:
- concrete demolition shear: For composite slabs, downstand beams, column encasements, and concrete infills; excellent control with low vibration levels.
- hydraulic splitter or rock wedge splitter: For massive components and masonry infills within the steel skeleton; they create predictable cracks and divide components into manageable segments.
- steel shear and hydraulic shear: For cutting structural steel, plates, bracing, and reinforcement; suitable for inner-city job sites with noise restrictions.
- Hydraulic demolition shear: When demolition of concrete and cutting of steel must alternate in successive steps.
- cutting torch: For thick-walled plates, tanks, or vessels in industrial buildings with steel-skeleton infrastructure.
- hydraulic power pack: Power supply for the tools; selection according to drive power, hydraulic hose line length, and deployment location.
Concrete demolition shear and hydraulic splitter in the steel skeleton context
In buildings with a steel skeleton, concrete slabs, toppings, and encasements form the interface between steel and mineral building materials. concrete demolition shear enable selective “biting” of the concrete structure (matrix) along steel beams without unnecessary damage to the profiles. hydraulic splitter divide thick components via controlled splitting forces, e.g., at downstand beams, bearing zones, or massive pedestals. Both methods are predestined for interior demolition and cutting as well as concrete demolition and special demolition when vibrations and dust must be minimized.
Composite slabs, downstand beams, joint areas
Typical sequence: remove the concrete layer in sections with concrete demolition shear, expose reinforcement, split to relieve stresses and reduce size, then cut steel at flanges/webs. This keeps load paths controllable and enables high-quality material separation.
Low vibration and precise
Hydraulic splitting and shear-based concrete demolition act locally and with low vibration levels. This is advantageous for sensitive neighbors, operations under use, or in historic steel-skeleton buildings.
Application areas at a glance
Steel-skeleton structures appear in various scopes of work. The connection with tools from Darda GmbH is particularly evident in the following application areas:
- concrete demolition and special demolition: Selective deconstruction of composite slabs, removal of concrete encasements, separation at joints.
- interior demolition and cutting: Interior strip-out down to the steel skeleton, preparation for conversion or new uses.
- rock excavation and tunnel construction: Interface of steel arches, support elements, and rock; controlled splitting of anchor blocks or bearing zones.
- natural stone extraction: For foundations with natural-stone masonry in conjunction with steel skeletons, splitting can ease separation.
- special demolition: Work in confined spaces, overhead, or with special emission requirements.
Structural and safety aspects
When working on the steel skeleton, structural stability is paramount. Cut sequences, temporary supports, and bracing must be planned to ensure load paths remain secured at all times. Work must be carried out by qualified personnel using suitable protective equipment; legal and occupational safety requirements must be observed. The following points have proven effective:
- Check load transfer and bracing before each separation cut; if necessary, provide temporary shoring.
- Work in sections; reduce components to manageable sizes.
- Consider residual stresses, particularly in welded or riveted profiles.
- Handle hazardous substance (e.g., old coatings, fireproofing materials) in a professional manner.
- Provide fall protection, plan anchorage points, and coordinate lifting device equipment.
- Reduce emissions with low vibration levels and dust suppression.
Materials and connection technology: consequences for the separation method
Depending on the profile type and connection, approach and tool selection change. Hollow sections and plates are well separated with steel shear or hydraulic shear, while massive joints often require preliminary work on concrete and targeted relief cuts. Riveted connections from early construction eras are particularly resilient; here, mechanical cutting with powerful shear is suitable. Thick-walled plate or tank components in steel-skeleton industrial buildings point to the use of a cutting torch. Hydraulic demolition shear are useful when fast switching between concrete removal and steel cutting is needed.
Sustainability, circularity, and material separation
Steel is almost completely recycling-friendly. The cleaner the separation, the higher the material quality. Targeted work with concrete demolition shear and the splitting of mineral components with hydraulic splitter allow concrete, reinforcement, and profiles to be separated by type. This supports efficient recovery, reduces transport volume, and helps conserve resources. Hydraulic methods act locally and can reduce noise and vibration, improving the carbon footprint (CO₂ balance) on site.
Practical site guidance
Organizational and technical details determine efficiency and safety. In practice, the following has proven effective:
- Expose joints and clearly mark cuts before starting separation work.
- Select the hydraulic power pack according to tool demand and hydraulic hose line lengths; perform leakage test and pressure checks.
- Plan logistics for disposal and intermediate storage to keep routes short.
- Communicate the cut sequence within the team; use unambiguous hand signals and exclusion zones.
- Account for weather and temperature, especially for exterior work on steel profiles.