Residual load-bearing capacity describes the remaining load reserve of a component or structure after a change in cross-section, after damage, or after targeted interventions such as sawing, splitting, pressing, or shear/cutter operations. In concrete demolition and deconstruction, it is a central criterion for structural stability, work organization, and tool selection. In particular, when using concrete demolition shears and rock and concrete splitters from Darda GmbH, the controlled introduction of forces determines the safe behavior of adjacent structural elements that must continue to carry loads from self-weight, use, and construction stages.
Definition: What is meant by residual load-bearing capacity
Residual load-bearing capacity is understood as the load-bearing resistance of a component after partial cross-section reduction, material damage, or load redistribution. It is therefore the difference between the original load-bearing capacity and the portions of capacity permanently lost due to interventions or damage. The governing criteria are the ultimate and serviceability limit states: bending, shear, punching, buckling, bond, and cracking. Residual load-bearing capacity is state-dependent and changes with the construction process—for example when creating openings, during gutting works, during controlled rock or concrete splitting, or during size reduction with concrete demolition shears.
Technical fundamentals of residual load-bearing capacity
Residual load-bearing capacity is derived from material properties (e.g., compressive strength of concrete, reinforcement contribution, masonry strength, rock quality), geometry (cross-section, slenderness), support conditions, and the current load situation. Interventions alter the structural system: cuts, drillings, and splitting joints weaken the cross-section; concrete demolition shears crush local areas; split cylinders generate separation cracks. This leads to load redistribution into adjacent members. The assessment considers partial safety factors, member imperfections, crack behavior, bond conditions, and material states (moisture, aging, corrosion). In construction stages, verification is often more critical than in the final state because temporary loads, eccentricities, or shoring can stress the resistance more.
Significance of residual load-bearing capacity in concrete demolition and special demolition
In deconstruction, the sequence of work steps must be adapted to the residual load-bearing capacity. Every cut, every split, and every jaw bite changes the stability of adjacent slabs, walls, columns, and beams. Tools by Darda GmbH—such as concrete demolition shears or rock and concrete splitters—enable low-vibration and controlled action, which can reduce load peaks and limit unplanned crack propagation. The decisive factor is the combination of analytical evaluation, construction-stage monitoring, and suitable temporary securing.
Influence of localized interventions
Local measures such as core drilling, chasing, splitting boreholes, or jaw placement points lead to cross-section weakening and new crack fields. For concrete demolition shears, compression zones and lever arms must be taken into account; for splitters, the position, depth, and direction of the splitting boreholes as well as the split wedges or cylinders. In this way, the crack pattern can be steered and the residual load-bearing capacity purposefully preserved.
Assessment and verification in practice
The practical determination is case-specific and step-by-step. Typical elements of an appropriate assessment are:
- Review of existing documentation, reinforcement and execution drawings; plausibility check of the structural system
- On-site inspection: crack mapping, deformations, signs of corrosion, moisture, support conditions
- Derivation of material parameters (e.g., via suitable tests or selective openings) and assumptions with safety margins
- Load assumptions for construction stages: self-weight, temporary live loads, machine loads, eccentricities, wind/vibration effects
- Calculation model with suitable idealization (members, supports, bond), verification of the governing limit states
- Definition of protective and safeguarding measures (shoring, propping, load rerouting) before starting the intervention
- Construction-stage monitoring and adjustment of measures when approaching thresholds
Influencing factors on residual load-bearing capacity
- Condition of the construction material: compressive strength, reinforcement ratio, corrosion, carbonation, moisture
- Geometry: cross-section, slenderness, recesses, existing openings
- Support and load paths: support reactions, restraints, bond between steel and concrete
- Crack distribution and crack widths from prior loading, temperature, restraints
- Vibration and dynamic effects from construction equipment and surroundings
- Sequence of works and extent of temporary securing
- Subsoil and rock-mass conditions in rock excavation and tunnel construction (joints, bedding, water)
Tool selection and working method depending on residual load-bearing capacity
The choice of tool influences the crack pattern, force transmission, and thus the remaining load reserve. The hydraulic power units from Darda GmbH allow reproducible pressure control to keep splitting or shear forces within safe ranges. The following principles have proven effective:
Concrete demolition shears: control force, steer crush zones
Concrete demolition shears generate concentrated compressive and shear forces. They are suitable for breaking components down piece by piece without applying impact shocks. For residual load-bearing capacity, the position of the bite point, the bracing of adjacent elements, and the successive reduction of cross-sections are decisive. For load-bearing walls and slabs, an early load transfer (shoring) must be planned before the shear engages.
Rock and concrete splitters: crack guidance and load limitation
Rock and concrete splitters act on a wedge- or cylinder-based principle and create predictable separation joints. Through drilling pattern, spacing, and splitting direction, crack propagation can be influenced so that load-bearing zones can be preserved. This is particularly useful for openings in slabs, for gutting works, and for massive members where low vibration is required.
Combination shears, multi cutters and steel shears
In mixed constructions with reinforcement or steel members, combination shears, multi cutters, and steel shears support targeted separation of metallic cross-sections. The load redistribution from the steel share into the remaining concrete sections must be considered in the residual load-bearing capacity; temporary suspensions may be required.
Tank cutters and material-adapted separation techniques
When cutting thin-walled, large-area components (e.g., vessels or tanks), stability phenomena shift: bulging, buckling, and local instabilities dominate. The safe sequence of cuts is crucial to deliberately preserve residual load reserves.
Temporary securing: shoring, underpinning, load rerouting
Residual load-bearing capacity is often only usable through temporary measures. Suitable means are:
- Posts, shoring props, shoring towers, and needle beams to take vertical loads
- Beam yokes, girders, and suspensions for load rerouting
- Edge and field shoring before opening slab fields
- Grouting and local strengthening to increase resistance
These measures must be designed in conjunction with the chosen working method (concrete demolition shears, splitter, cutting) and installed before the intervention.
Monitoring of residual load-bearing capacity during the intervention
Construction-stage monitoring increases safety and responsiveness:
- Measurement of deflections and settlements at governing members
- Crack monitoring (crack widths, crack growth)
- Control of support forces and hydraulic pressures
- Documentation of sequences and threshold management
The hydraulic power packs from Darda GmbH support controlled force introduction; limit pressures can be maintained procedurally so as not to exhaust residual load reserves.
Residual load-bearing capacity in rock excavation and tunnel construction
In rock masses, joints, bedding, discontinuities, and water flow govern stability. Rock and concrete splitters enable targeted crack guidance along existing weaknesses and reduce vibrations that might otherwise trigger uncontrolled crack propagation. For crown and face support, short advances, immediate securing, and tuned splitting energy are decisive to maintain the residual load-bearing capacity of the rock in every construction phase.
Residual load-bearing capacity in natural stone extraction
When freeing blocks, orientation to bedding joints and the sequence of longitudinal and transverse splits are decisive. A coordinated borehole geometry and moderately increased splitting forces preserve the intact areas of the raw block and the stability of the quarry face. This reduces the risks of unintended fracture progress.
Strip-out and cutting: controlling construction stages
Removing non-load-bearing components can relieve load-bearing systems—or overstress members through load redistribution. When sawing openings in slabs and walls, the sequence of cuts must be coordinated with the position of temporary supports. Concrete demolition shears are suitable for the subsequent downsizing, provided the residual load-bearing capacity is secured by prior shoring.
Occupational safety, standards and responsibilities
The assessment of residual load-bearing capacity is fundamentally carried out through expert planning and supervision. Standards on structural stability, deconstruction, and work equipment provide boundary conditions; in individual cases, the safety margins and construction-stage verifications described therein are decisive. The information given here is general and does not replace a project-specific check. What matters is the coordinated interaction of planning, structural analysis, execution, and supervision.
Typical mistakes and how to avoid them
- Underestimating construction stages: missing shoring before opening load-bearing components
- Inappropriate tool selection: impact methods despite low residual load-bearing capacity
- Unplanned load redistribution due to asymmetric cuts or shear jaw placement
- Insufficient monitoring and missing threshold definitions
- Work segments that are too large without intermediate propping
- Neglecting boundary conditions such as moisture, corrosion, or vibrations
Documentation and quality assurance
A structured documentation improves traceability and safety:
- Site-specific concept for residual load-bearing capacity with verifications for construction stages
- Releases for each construction section, including specifications for concrete demolition shear and splitter parameters
- Measurement and test plan with thresholds and actions in case of exceedance
- Photo documentation of crack development and temporary securing
- Final evaluation and lessons learned for follow-up projects
Key values and practice-oriented notes
For robust planning, use conservative material parameters, appropriate partial safety factors, and clear assumptions for load distribution. Small, controlled work steps, moderate hydraulic pressures, and close-knit monitoring are, in practice, more effective than large-scale interventions. Tools from Darda GmbH—particularly concrete demolition shears and rock and concrete splitters—support a forward-looking strategy that deliberately preserves residual load reserves and keeps construction stages under control.