The load-bearing shell is a central element of many structures: it takes up loads, transmits forces safely into the structural system, and thus separates load-bearing functions from protective or design layers. In multi-layer wall assemblies, sandwich elements, and tunnel structures, it decisively determines structural stability, durability, and the deconstruction sequence. In concrete demolition, special demolition, interior demolition, as well as in rock excavation and tunnel construction, competent handling of the load-bearing shell has direct effects on occupational safety, building physics, and quality. Tools such as concrete pulverizers or hydraulic rock and concrete splitters (wedges) from Darda GmbH are frequently used to separate load-bearing and non-load-bearing layers in a controlled manner or to dismantle them selectively.
Definition: What is a load-bearing shell
A load-bearing shell is the load-bearing layer of a multi-layer component — for example, the inner leaf of a double-leaf external wall or the primary lining of a tunnel structure — that performs the structural tasks. It carries dead, live, and wind loads, and, where applicable, earth and rock pressure, and transfers them via supports, slabs, or foundations into the structure. Non-load-bearing layers such as facing shell, veneer masonry, or interior fit-out usually serve weather protection, aesthetics, fire protection, or improved thermal and sound insulation. In concrete sandwich walls, depending on the design, the inner or outer concrete shell can be configured as the load-bearing shell; composite action is then provided via shear connectors and anchors.
Configuration and design principles of the load-bearing shell
The load-bearing shell is designed so that its load transfer and deformability take precedence over the other component layers. Typical are reinforced concrete or masonry sections with defined connection details. In double or sandwich walls, wall anchors, stainless steel brackets, or fiber connectors ensure coupling to the facing shell; in tunnel and cavity structures, shotcrete linings act as the primary support. Expansion joints (movement joints), thermal breaks, waterproofing layers, and core insulation are arranged so that they do not impair the load-bearing action. The decisive point is controlled force transfer: point-, line-, or surface-wise — each tailored to geometry, building physics, and construction states during erection, use, and deconstruction.
Load-bearing shell in facades and external walls
In external walls, the inner leaf is often the load-bearing layer, while the outer facing shell provides weather protection and architectural expression. In concrete sandwich elements, the inner concrete shell can serve as the load-bearing shell; core insulation and connectors complete the build-up. In masonry facades, the inner masonry layer (e.g., calcium silicate brick or brick) performs this role, while veneer masonry protects and articulates. In refurbishments and energy retrofits, understanding the load-bearing shell is essential to create openings, plan load redistribution, or install anchors for new components.
Selective deconstruction at the facade
During deconstruction, the facing shell and interior fit-out are separated first before intervening in the load-bearing shell. Concrete pulverizers enable low-vibration removal of reinforced concrete areas, e.g., at lintel and parapet zones. Hydraulic rock and concrete splitters (wedges) with suitable splitting cylinders generate defined crack patterns to release wall panels in a controlled manner. Mobile hydraulic power units from Darda GmbH supply these tools quietly and efficiently, which is especially advantageous in sensitive existing environments.
Load-bearing shell in tunnel construction and underground structures
In tunnel construction, a distinction is made between primary support (shotcrete lining, rock bolts, lattice girders) and secondary inner lining (usually reinforced concrete). Depending on the excavation method (e.g., cyclic tunnel heading, shotcrete method), the outer lining takes the immediate load uptake from the ground and rock pressure. The inner lining serves durability, waterproofing, and final shaping; in certain concepts, it also assumes load-bearing tasks. In rehabilitations or cross-sectional enlargements, targeted processing of the load-bearing lining is a core task that requires low vibration levels and controlled cutting paths.
Tools for tunnel and rock operations
For rock demolition and tunnel construction, hydraulic rock and concrete splitters (wedges) prove effective because they work without explosives and induce cracks along the desired lines. In reinforced inner linings, concrete pulverizers are used for removal and to expose reinforcement; steel shears or combination shears then cut the exposed steel parts. This approach supports a controlled construction sequence and reduces the impact on adjacent components.
Materials and typical cross-sections
Depending on the task, load-bearing shells consist of reinforced concrete, prestressed concrete, masonry, shotcrete, or hybrids. The section is designed for bending, shear, and, where applicable, axial force. In sandwich panels, non-metallic shear connectors are used to minimize thermal bridges; in masonry composites, corrosion-resistant wall anchors ensure the connection to the outer shell. Durability depends on concrete quality, concrete cover, mortar class, moisture exposure, and corrosion protection.
Typical details
- Supports and brackets: load-transferring connections of the load-bearing shell to slabs or columns
- Shear connectors and wall anchors: define composite action between shells
- Core insulation: thermal separation without impairing structural action
- Joints and expansion zones: limit restraint stresses and cracking
- Waterproofing layers: protect components without disturbing load-bearing action
Design and verification for the load-bearing shell
The design of a load-bearing shell is based on structural analysis, fatigue and serviceability checks, as well as building physics assessments. For existing buildings, documentation, probes, and opening-up investigations are crucial. Test options include rebound hammer testing, rebar scanning, endoscopic inspections, or core drilling. Before intervening in the load-bearing shell, load paths and construction states must be assessed; safeguarding measures such as shoring may be required. Legal requirements, permits, and occupational safety specifications are project-specific and should always be considered in coordination with designers and specialist site management.
Deconstruction, interior demolition, and cutting on the load-bearing shell
Selective deconstruction first separates non-load-bearing layers from the load-bearing shell before adapting or removing load-bearing areas. In interior demolition and cutting, low-dust, low-vibration methods are advantageous. Concrete pulverizers allow step-by-step removal and exposure of reinforcement without heavily stressing adjacent components. Hydraulic rock and concrete splitters (wedges) create crack lines for predetermined breaking joints, particularly in thick walls or foundations. Hydraulic power packs from Darda GmbH provide the required energy; combination shears and steel shears help cut profiles, reinforcement, or embedded items. Multi Cutters support universal cutting tasks, while tank cutters can be used in special operations, for example, where vessels or building services components are integrated into the load-bearing wall shells.
Advantages of controlled methods
- Low vibrations and reduced noise emissions
- Precise separation joints and minimized damage to the remaining load-bearing structure
- Targeted exposure of connections, anchors, and reinforcement
- Improved material purity for recycling through clean separation of layers
Typical damage patterns in load-bearing shells
In practice, cracks occur due to restraint, settlement, or moisture variations; in concrete, rebar corrosion with spalling is a frequent finding. In sandwich constructions, connectors may corrode or composite action may be lost. Masonry load-bearing shells occasionally show shear cracks at opening corners or moisture damage in the base/plinth area. Proper diagnosis combines visual inspection, measurements, and, where necessary, low-invasive investigations. Rehabilitation equally considers load-bearing capacity, durability, and building-physics effects.
Interfaces to products and application areas
Depending on the task, different devices from Darda GmbH are used in connection with load-bearing shells:
- Concrete pulverizers: controlled removal of reinforced concrete at openings, lintels, parapets, wall panels (use: concrete demolition and special demolition)
- Hydraulic rock and concrete splitters with splitting cylinders: low-vibration splitting of massive wall and foundation areas as well as rock (use: rock excavation and tunnel construction, natural stone extraction)
- Hydraulic power packs: energy supply for mobile tools on tight construction sites or in existing buildings (use: interior demolition and cutting, special operations)
- Combination shears, steel shears and Multi Cutters: cutting reinforcing steel, profiles, brackets, and embedded parts in and on the load-bearing shell (use: interior demolition and cutting)
- Tank cutters: processing of vessels or pipes integrated into load-bearing wall shells (use: special operations)
Execution notes and occupational safety
Work on the load-bearing shell affects structural stability. Before starting, clarify structural boundary conditions, avoid load redistribution, and provide temporary shoring. The cut sequence, demolition scheme, and the positions of joints, anchors, and reinforcement must be documented. Personal protective equipment, dust and noise reduction measures, and safe access must be ensured. For prestressed components, large-format sandwich panels, and tunnel linings, special expertise is required; interventions should always be planned and supervised by qualified personnel.
Sustainability and circularity aspects
Clear separation of load-bearing shell and facing shell supports material recycling and reuse. Low-vibration methods such as splitting and shearing reduce dust, noise, and secondary damage. Clean separation of concrete, masonry, insulation materials, and metal connectors increases the quality of recyclate streams and lowers disposal costs. At the same time, the remaining load-bearing structure is better preserved, facilitating refurbishment and partial repurposing.