Structural steel sections are the backbone of many load-bearing structures—from steel hall construction and composite slabs to tunnel linings. In planning, assembly, maintenance, and especially during deconstruction, cross-section, material, and connections determine how efficiently and safely work can be performed. Particularly in concrete demolition, special demolition, and strip-out, the professional exposure, cutting, and dismantling of structural steel sections play a central role. Depending on the construction task, hydraulic tools from Darda GmbH are used—for example, concrete demolition shears to break out and expose concrete on composite members, as well as steel shears or multi cutters to cut the steel sections. rock and concrete splitters from Darda GmbH assist when massive components must be opened with low vibration levels or unloaded.
Definition: What is a structural steel section
A structural steel section is a bar-shaped, load-bearing member, usually made of steel, with a defined cross-section (profile). Common shapes are I- and H-sections (wide-flange beams), U-sections, L-sections (angles), T-sections, and hollow sections (square, rectangular, or circular tubes). Structural steel sections transfer bending, shear, and compressive forces, serve as primary or secondary members, and are used both as pure steel construction and in composite construction with concrete. Load-bearing capacity depends on cross-sectional geometry, steel grade, span, support conditions, and connection details.
Site practice: structural steel sections in deconstruction and strip-out
In deconstruction, structural steel sections often come into focus as load-bearing elements. In existing buildings, they are often concealed behind claddings, fire protection layers, or integrated into concrete members. For safe dismantling, load paths are first redirected, supports are secured, and adjacent materials are selectively removed. Darda concrete demolition shears separate concrete locally and create fracture edges that expose rebar and the connected structural steel sections. Steel components are then segmented with steel shears, combination shears, or multi cutters. hydraulic power units provide the necessary performance, even in confined areas, as often encountered during strip-out. In this way, structural steel sections can be released in sections, manageable unit weights can be produced, and cleanly separated material streams can be prepared for disposal.
Types and geometries of structural steel sections
The choice of section form follows the loading and the construction method. In practice, identifying the cross-section is crucial, because exposure, cutting path, and tool selection depend on it.
- I-/H-sections (wide-flange beams): High bending stiffness, often used as primary beams. Preferred cut in the web due to lower thickness.
- U-sections: Used as edge or frame sections; beware of torsionally flexible behavior when releasing connections.
- L-sections (angles): Connection and bracing elements; usually thinner-walled, readily cut with shears.
- T-sections: Often cut down from other sections; consider asymmetric cross-sections.
- Hollow sections (RHS/SHS/CHS): High torsional stiffness; when cutting, watch for elastic snap-in—provide pilot holes or V-cuts if needed.
Composite construction: steel sections in concrete
In slabs and bridges, structural steel sections are often coupled with concrete to form composite members, for example via headed shear studs or embedment. For deconstruction this means: first expose the concrete, then release the steel connection. Concrete demolition shears from Darda GmbH are suitable for removing concrete layer by layer and making reinforcement and shear studs visible. Stone and concrete splitters enable low-vibration openings in thick members without damaging adjacent structures. After exposure, structural steel sections can be cut into transportable lengths with steel shears or multi cutters. Watch out for residual composite zones, undergrouting, and grout mortar at supports—here a controlled sequence of relief cut, unloading, and final cut is sensible.
Tool selection and cutting strategies
The selection of the hydraulic tool depends on section type, wall thickness, accessibility, and required cycle.
- Concrete demolition shears: For selective removal of concrete on composite members, opening edge areas, and exposing connections.
- Steel shears: For cutting massive sections, including HEB/IPE; start the cut in the web, then proceed into the flanges.
- Combination shears / multi cutters: Flexible with mixed materials (steel, rebar, light sections) and ideal in strip-out.
- Hydraulic power packs: Provide pressure and flow to suit demand; long hydraulic hose lines enable work in hard-to-reach areas.
A sequence of pre-exposure, unloading, starter cut, final cut has proven effective. For hollow sections, V-shaped incisions can reduce jamming. For coated or corroded sections, brief pre-cleaning in the cutting area is helpful.
Workflow in the special demolition of structural steel sections
Investigation and assessment
Before starting, drawings, material data, and as-built conditions are reviewed. Fastenings (anchor plates, weld seams, bolted joints), fire protection systems, and potential composite action with concrete must be identified. Test cuts and wall thickness measurements support tool selection.
Load transfer and safeguarding
Temporary shoring creates safe conditions. Cutting begins only after load paths have been redirected. This step follows a structural concept and is carried out under the supervision of qualified specialists.
Exposure and cutting
Darda concrete demolition shears remove concrete down to the steel. Cutting then proceeds with steel shears or multi cutters. Hydraulic power packs supply the tools continuously, including for vertical and overhead work.
Unit weight and handling
Segments are dimensioned so that cranes or lifting devices are available and logistics fit escape and transport routes. Edges are deburred or protected to avoid injuries and damage.
Structural steel sections in tunnel construction and rock excavation
In tunnel construction, lattice arches, TH- or H-sections are combined with shotcrete as temporary support. During deconstruction or cross-section enlargements, shotcrete layers are first selectively removed with concrete demolition shears. The structural steel sections can then be cut with steel shears at the crown and at the springlines. Stone and concrete splitters support controlled release from rock contacts when vibrations must be avoided, for example in sensitive areas or during special operations near existing infrastructure.
Factors influencing the cutting technique
- Steel grade and wall thickness: Higher strengths and thick flanges require greater cutting forces.
- Coatings: Fire protection, bitumen, cement plasters influence the cutting path; exposure improves process reliability.
- Corrosion: Can make the material brittle; stabilizing gripping technique and short cutting paths are advantageous.
- Connections: Release bolted, riveted, or welded joints in a targeted manner, or cut them together with the section.
Planning the cutting path
For straight members the recommendation is: start centrally in the web, carry the cut through, then separate the flanges individually. At nodes with multi-layer plates, staggered cuts are useful to minimize clamping forces. In composite slabs, first open the concrete topping with concrete demolition shears, then expose the shear studs and remove them in a targeted way or cut them along.
Safety and protective measures
Work on load-bearing structural steel sections requires coordinated measures: approved shoring, defined exclusion zones, lifting and rigging equipment as specified, and personal protective equipment. Cutting and splitting processes create fracture edges, splinters, and pressure peaks; a planned, calm work rhythm and clear hand signals increase safety. Legal and normative requirements must be checked on a project-specific basis; concrete procedures should always be defined through expert planning.
Disposal and resource conservation
Steel from structural steel sections is a valuable secondary raw material. Clean separation from concrete, mortars, and coatings increases the quality of the fractions. The use of concrete demolition shears as well as stone and concrete splitters from Darda GmbH reduces dust, vibrations, and noise, which supports environmental and neighborhood protection. Handy lengths simplify logistics and increase throughput on the demolition day.
Typical challenges and practical solutions
- Hidden connections: Selective exposure with concrete demolition shears, marking all connection points, only then cutting.
- Hollow sections with residual water or fill: Open and drain before cutting; limit snap-in by using a V-cut.
- Confined conditions: Use compact shears and powerful hydraulic power packs; adapt the cutting sequence to accessibility.
- Structural steel sections on tank support structures: Separating the adjacent plate construction (e.g., with suitable cutting tools such as tank cutters from Darda GmbH) creates access; the sections are then cut to length.
Surveying and documentation
A simple yet effective practice is marking all cutting interfaces on the section. Wall thickness measurements, photo documentation of connections, and a brief cutting plan support coordination of crew, equipment, and disposal. This keeps the process transparent and reduces rework.