Beam connections are the nodes of a load-bearing structure where steel or composite beams take loads, transfer them, or are mounted as pinned supports. In planning, repair, refurbishment, and deconstruction, the quality of these connections determines safety, construction sequence, and cost efficiency. In the context of concrete demolition and special demolition, strip-out and cutting, as well as special operations, beam connections are frequently exposed, separated, strengthened, or completely removed. Hydraulic methods with precise, low-vibration tools—such as concrete pulverizers or hydraulic rock and concrete splitters—have proven effective in providing visibility of the connection details and making the steel cross-sections accessible for subsequent cutting.
Definition: What is meant by beam connection
A beam connection is the constructive design of the connection of a beam to another structural element, for example to a column, a girder, a wall bracket, or an adjacent beam. Depending on the structural function, the connection can be moment-resisting (rigid), shear-resisting (primarily shear transfer), or largely pinned. In steel and composite construction, beam connections consist of plates, end plates, fin plates, bolts, welds, shear connectors (e.g., headed studs), and, where applicable, concrete bearings. Existing structures may also feature riveted connections or embedded steel parts. For deconstruction, the type, accessibility, and load transfer of the connection are decisive for the choice of the cutting or demolition method.
Design variants: types, details, and identifying features
Beam connections differ according to material, fabrication method, and structural action. Knowing typical construction methods facilitates assessment, exposure, and cutting operations in existing structures.
- Bolted connections: End plates, angle or fin-plate connections with high-strength bolts. Identifiable by visible rows of heads/nuts, often with preloaded bolts. Advantages in deconstruction: defined removability, but often corroded or encased in concrete.
- Welded connections: Butt or fillet welds between beam flanges/webs and connection plates or column heads. In deconstruction they require precise steel cutting, often with steel shears or multi cutters.
- Riveted connections: In older buildings; tough connection, high residual forces. Prefer cutting by shearing or segmental removal.
- Composite connections: Steel beams with shear studs embedded in a reinforced concrete slab. Concrete pulverizers are ideal to remove the concrete around the headed studs in a controlled manner; steel parts are then separated.
- Embedded bearings: Bearing brackets, steel angles, or bearing blocks cast in concrete. Hydraulic splitters enable low-vibration exposure without extensive percussive work.
- Timber–steel hybrids: Less common in heavy deconstruction but relevant in refurbishments; frequently screw/dowel connections with steel parts.
Structural behavior and design aspects at a glance
The structural function of a beam connection determines procedure and sequencing in deconstruction. Rigid nodes transfer moments via flange connections and shear via the web; pinned connections concentrate shear transfer at the web. Consider load paths, ductility, slip in bolted connections, notch effects at welds, and bearing pressure at concrete supports. Before cutting operations, plan temporary shoring or load redistribution; this is especially important for composite beams whose load-bearing capacity can drop abruptly when the shear connectors are released.
Existing-structure investigation: capture, assessment, and documentation
Before intervening at beam connections, review design documents, perform condition assessments, and conduct low-damage investigations. Visual inspections determine type, accessibility, degree of corrosion, and defects (e.g., cracks at fillet welds, plastic deformations, fire damage). Hidden details, such as embedded plates, can be gently exposed by construction-accompanying removal with concrete pulverizers or by hydraulic splitting. For documentation, photos, dimensioned sketches, and load assumptions are useful. Legal and standard requirements must be observed in general; project-specific verifications should be provided by qualified designers.
Interventions in refurbishment and deconstruction: proceeding at beam connections
Whether openings in composite slabs, separation cuts in steel beams, or selective deconstruction of entire nodes: the method depends on connection type, available space, and emission requirements (noise, dust, vibration).
Selective deconstruction during strip-out
- Exposure: Remove concrete locally with concrete pulverizers, perform controlled rebar cutting, and expose shear connectors.
- Relieving: Install temporary shoring, redistribute loads, and check hangers.
- Separation: Cut steel members with steel shears, Multi Cutters, or combination shears; for thick plates, use segmental removal. For large cross-sections, multi-stage cuts are advisable.
- Segmenting: Break nodes down into manageable parts, follow a defined sequence, and consider residual stresses.
Composite slabs and headed studs
For composite beams, releasing the shear connection is the critical step. Local, low-vibration concrete removal using concrete pulverizers or hydraulic splitters prevents uncontrolled crack propagation and reduces secondary damage. The exposed steel parts can then be separated with steel shears or multi cutters.
Tools and methods around beam connections
Hydraulic drives and compact cutting/splitting tools are advantageous in tight existing conditions. They enable precise work with low vibration and minimal sparking.
- Concrete pulverizers: Selective concrete removal at bearings, brackets, and composite joints; provides visibility of shear connectors and connection plates.
- Hydraulic splitters: Inducing cracks in concrete with low vibration; ideal for releasing embedded steel parts and relieving before cutting.
- Steel shears: Cutting profiles, end plates, gusset plates, and rebar; clean cuts without thermal influence.
- Combination shears and multi cutters: Flexible for mixed tasks of cutting, crushing, and pulling; useful at heterogeneous nodes.
- Cutting torch: For thick plates and high-strength steels in special cases, e.g., massive steel nodes or special components.
- Hydraulic power pack: Supplies the tools with the required output; select by pressure, flow rate, and the parallel operation of multiple consumers.
Safety, emissions, and boundary conditions
Work at beam connections intervenes in the load-bearing system. Verified work and rescue plans, defined exclusion zones, and robust communication are necessary. Emissions such as noise, dust, and vibration can be reduced by hydraulic cutting and splitting methods. In potentially fire- or explosion-prone areas, consider sparking and media (oils, gases). Legal requirements must generally be observed; concrete measures depend on the specific project and must be defined by qualified planners.
Typical damage patterns at beam connections
- Corrosion at bolts, end plates, and fin plates; cross-section loss, reduced preloading.
- Cracking in fillet welds or at notches; risk of brittle fracture under cyclic loading.
- Settlement and bearing spalling at concrete supports; nonuniform pressure, rotations.
- Fire damage: Microstructural changes in steel, spalled concrete at composite joints.
- Assembly errors: Insufficient clamping length, wrong bolt grades, missing washers.
Planning steps for interventions at beam connections
- Investigation: Review documents, locate nodes, assess accessibility.
- Exposure concept: Plan selective concrete removal with concrete pulverizers or splitting techniques; define protection for the surroundings.
- Temporary securing: Shore, relieve, and define load redistributions.
- Cutting strategy: Define sequence of cuts, tool selection (steel shears, multi cutters, combination shears), and segment sizes.
- Execution: Mark cut lines, monitor cutting forces, release the node step by step.
- Follow-up: Deburr edges, prepare deconstruction surfaces, and separate residual materials by type.
Application areas of particular relevance
In concrete demolition and special demolition, composite nodes and embedded steel parts are the focus; concrete pulverizers and hydraulic splitters minimize vibration. In strip-out and cutting, selective separation cuts at steel nodes with steel shears and multi cutters dominate. In special operations—such as confined access or sensitive existing structures—compact hydraulic tools and finely controllable hydraulic power units are advantageous. In rock excavation and tunnel construction, beam connections occur on temporary linings or auxiliary structures; here, controlled dismantling of connection parts after the construction phase is relevant.
Terms and key parameters for beam connections
- End plate, angle/fin-plate connection, gusset plate: Geometries of connection pieces.
- Bolt strength, preload, slip: Parameters of bolted connections.
- Fillet and butt welds: Weld types with different capacities and testing requirements.
- Shear connectors (e.g., headed studs): Ensure composite action between steel beam and concrete slab.
- Bearing pressure, contact stiffness: Influence on deformations and cracking at the bearing.
- Ductility and residual load-bearing capacity: Decisive quantities for controlled release in deconstruction.