The stability verification is the central instrument for ensuring the load-bearing capacity and serviceability of structures and structural elements in all construction stages. It is not only relevant in new construction, but especially in concrete demolition and special demolition, in building gutting and cutting, in rock excavation and tunnel construction as well as in natural stone extraction. Wherever components are deliberately separated, cut, or split — for example with concrete pulverizers or hydraulic wedge splitters — the load path changes. The verification systematically evaluates these changes to prevent overturning, sliding, buckling, punching shear, or progressive damage and to align execution with safe demolition and separation sequences, temporary shoring, and suitable demolition methods.
Definition: What is meant by stability verification
A stability verification is the analytical and conceptual confirmation that a structure resists the governing actions with adequate safety. It typically covers the Ultimate Limit State and the Serviceability Limit State, considers material behavior and load combinations, and differentiates between permanent and temporary construction states. In deconstruction, transitional states resulting from separation cuts, partial removals, staged sections, and auxiliary structures are additionally considered. Typical issues include global stability verification, sliding safety, overturning safety, punching shear and shear verification, load-bearing capacity of shoring, as well as the assessment of vibrations, deformations, and crack formation in the surroundings.
Application context: stability verification in concrete demolition and special demolition
In selective deconstruction, the load-bearing structure is altered step by step. Tools such as concrete pulverizers generate concentrated compressive and shear stresses at component edges, while hydraulic wedge splitters build up internal tensile stresses through wedge-shaped spreading forces. These processes are usually associated with low vibration levels, but they require a robust verification of the intermediate states: Which load paths remain active, how do internal forces change, where is temporary shoring required, and which segment sizes are permissible for safe handling? The stability verification provides the basis for this — from choosing the demolition sequence through the sizing of auxiliary shoring to defining permissible tool positions and forces. Hydraulic power packs (Power units) that supply the tools are considered in planning with regard to the maximum process forces to avoid local overloading.
Normative foundations and responsibilities
The verification follows the relevant technical rules and standards, which generally distinguish between permanent, variable, and accidental actions and provide special safety concepts for temporary states. Responsibilities usually lie with qualified structural engineers in coordination with site management and specialist site management for deconstruction. The executing parties implement the specified measures and document deviations. Legal requirements and approval needs may vary by project and location; statements here are always general in nature and non-binding.
Methodology of verification: step by step
- Survey of existing conditions: Record structural system, material properties, reinforcement layout, joints, damage, load paths, and connection points.
- Definition of construction states: Establish the initial state, intermediate states for each demolition step, and the final state with temporary auxiliary structures.
- Determine actions: Self-weight, live loads, wind load, temperature, equipment loads, process-related forces (pulverizer clamping pressure, splitting forces, cutting forces), and dynamic effects.
- Create calculation models: Choose suitable substitute systems (frame, plate, slab, or 3D models), load combinations, and material models.
- Perform verifications: Load-bearing capacity, serviceability, sliding/overturning, bearing pressures, punching shear, stability of auxiliary structures.
- Derive measures: Demolition sequence, segment sizes, positioning points for concrete pulverizers, positions of hydraulic wedge splitters, shoring, catch and safety measures.
- Monitoring and adaptation: Define measurement concept, tolerances, intervention and stop criteria; feed insights back into the workflow in real time.
Actions and load cases in deconstruction
For structural stability, in addition to self-weight and environmental actions, process-specific loads and redistributions are crucial. These include local introduction forces from hydraulic tools, load transfers due to separation cuts, dynamic impulses when releasing component segments, and lifted loads on the crane.
Tool-specific actions
- Concrete pulverizers: Local compression and shearing at edges; dimension the remaining cross-sections and avoid unintended notch effects with regard to punching shear and shear capacity.
- Hydraulic wedge splitters: Radial splitting forces; verification against uncontrolled crack propagation, securing of adjacent bearing lengths, and checking the sliding safety of component blocks.
- Combination shears, multi cutters, steel shear, concrete pulverizers: Cutting and separation forces in reinforcement and sections; control of global bracing when bracing members and ties are affected.
- Cutting torch: Local weakening in shell walls; stability verifications against buckling and local buckling phenomena.
Temporary states and auxiliary structures
Temporary shoring, transfer beams, support scaffolds, and tension members are often decisive. Their verification includes load-bearing capacity, deformation, bearing pressures, and safe load transfer into the subsoil. Anchor rails, anchor bolts, and bearing points must be dimensioned to also accommodate peak loads from non-uniform removal. Particularly critical are transitions in which diaphragm action is lost (e.g., due to wall openings) or when slab edge fields turn into cantilevers.
Example: verification for a ceiling opening
- Capture the slab as a plate system, document supports and reinforcement.
- Dimension shoring on both sides of the future opening; perform punching shear verification at columns near the opening.
- Define the sequence of separation cuts: Pre-cuts, then sectional nibbling with the concrete pulverizer; limit segment sizes based on the lifting device and residual load-bearing capacity.
- Check serviceability: Limit deformations in adjacent spans; crack-width control, especially at corbels and supports.
- Remove shoring step by step, under observation (dial gauges/settlement points) and with documented release.
Structural stability in rock excavation and tunnel construction
In rock demolition and tunnel construction projects, rock splitting cylinders influence block geometry and joint activation. The verification considers the overturning safety of blocks, sliding on joint planes, wedge stability, as well as protections by rock bolts, nets, and temporary supports. For splitting methods, the position of the drill holes is chosen so that controlled cracks develop and no impermissible load redistributions occur in linings, shotcrete, or lining elements.
Safe deconstruction of steel and composite structures
Steel shear, hydraulic shear (demolition shear), and cutting torch separate sections, beams, and tanks. Structural stability depends on the remaining bracing, transverse ties, and connection details. Verifications must cover buckling, overturning, flexural buckling, plate buckling, and the residual load-bearing capacity of composite sections after releasing shear connectors. Cut sequences are planned to preserve load paths and bracing routes for as long as possible.
Documentation, monitoring, and communication
A practical stability verification also defines monitoring. This includes monitoring points for settlements and inclinations, crack monitoring, thresholds, and intervention plans. On-site changes — such as differing reinforcement layouts or material strength — are documented and lead to an adaptation of the verifications before the next work step is released.
Typical pitfalls and prevention
- Failure to consider intermediate states, resulting in instability.
- Underestimated process forces from concrete pulverizers or hydraulic wedge splitters at sensitive cross-sections.
- Demolition sequences that remove diaphragm or frame action too early.
- Insufficient anchoring of temporary shoring and missing verifications for bearing pressures.
- Overlooked actions from crane lifts, wind load on exposed components, and thermal expansion.
- Unclear communication between planning and execution without defined stop criteria.
Practical tips for method selection with structural stability in mind
- Concrete pulverizers are preferable when controlled edge reduction with low vibration levels is required; verify remaining cross-sections early.
- Hydraulic wedge splitters are suitable for massive components when noise and low vibration levels are the priority; select splitting hole spacing to avoid uncontrolled crack propagation.
- Use multi cutters and attachment shear to selectively separate reinforcement and embedded parts and to steer load redistributions.
- Use steel shear and cutting torch with attention to global bracing; make cuts on bracing elements only after temporary securing.
Relation to application areas
Concrete demolition and special demolition
Selective demolition requires verifications for every intermediate step. Tools with hydraulic pulverizing or splitting action enable low-vibration methods; decisive are verifications of residual load-bearing capacity and safe demolition sequences.
Interior demolition and cutting
When removing non-load-bearing layers, global structural stability remains, but local verifications for openings, separation cuts, and breakthroughs are required. Cutting and pulverizer forces must be considered in the construction state.
Rock excavation and tunnel construction
Here, structural stability means safely releasing defined blocks, controlling joint systems, and temporarily securing the tunnel face. Splitting devices support controlled removal at reduced vibration levels.
Natural stone extraction
In the extraction of natural stone, blocks are won via splitting forces. The verification evaluates overturning safety, sliding, and the stability of remaining slopes, including temporary support measures.
Special demolition
In exceptional situations — such as damage events or sensitive environments — controlled, low-vibration methods take priority. The verifications define intervention limits, monitoring, and redundant safeguards.
Quality of verifications and on-site readability
A good stability verification is technically correct and at the same time understandable for execution. Drawings and texts show the demolition sequence, permissible segment weights, positions of shoring, permissible positioning points for concrete pulverizers, and the location of drill holes for hydraulic wedge splitters. Short, unambiguous instructions on the component minimize misinterpretations and increase safety.