The experimental specimen represents a large-scale (1:1.25), three-storey timber structure designed to investigate the effects of clutched inerter devices and rounded toes on the seismic response of post-tensioned cross-laminated timber (CLT) rocking wall systems. The structure consists of multiple materials and subsystems that interact to achieve a controlled and representative dynamic response under seismic loading. These include a gravity load-bearing system formed by glued laminated timber (Glulam) beams and columns, horizontal CLT floor diaphragms, CLT rocking walls serving as the primary lateral load-resisting system and U-shaped flexural plates providing energy dissipation. The structure has a total height of 5.40 m, distributed over three storeys with a uniform storey height of 1.80 m, and a consistent structural layout with maximum plan dimensions of 4.24 m × 4.43 m. The specimen was rigidly connected to the shaking table through a steel base beam assembly.

The gravity framing system comprises glulam columns and beams of varying cross-sections, supporting CLT floor slabs composed of three layers with a total thickness of 100 mm. The floor slabs were designed to act as rigid in-plane diaphragms and consist of prefabricated CLT panels connected to each other through half-lap joints fastened with 8x80 TBS screws at 90 mm intervals, and to the supporting beams using 180 mm TBS long screws anchored into the beams. Beam–beam and beam–column connections within the timber gravity frame were realised using aluminium connectors combined with self-drilling screws and dowels connections, ensuring reliable force transfer. Additional mass was installed at each floor level using steel ingots to reproduce realistic seismic inertial demands. The mass layout was identical across all floors. Ten ingots, each weighing 400 kg, were placed on every floor, resulting in an added mass of 4 t per storey and 12 t in total.

The CLT rocking walls include one internal central wall and two external perpendicular walls, noted as Wall A and Wall B, enabling investigation of both in-plane and out-of-plane rocking response. The walls extend over the full specimen, with height of 5.62 m and are connected at each floor level through lateral holders, shear keys and U-shaped flexural plates which enable force transfer while avoiding unintended restraint of the rocking mechanism. The internal wall had a thickness of 160 mm and consisted of five layers whereas each external wall had a thickness of 80 mm and consisted of three layers. The internal wall was detailed with traditional flat toes, while the external walls were detailed with rounded toes. Controlled rocking is achieved by permitting uplift at the wall base once the overturning moment exceeds the restoring contributions of gravity and post-tensioning forces. Self-centring capability is provided by four vertical post-tensioning bars per wall. The internal wall was post-tensioned to 30 kN per bar, resulting in a total post-tensioning force of 120 kN, while each external wall was post-tensioned to 15 kN per bar, corresponding to 60 kN per wall and 120 kN combined. Energy dissipation was provided through U-shaped steel flexural plates installed at each floor level on both sides of every wall, resulting in six dissipators per wall.

Two supplemental inerter devices were incorporated only in specific experimental configuration. They were installed at the first-floor level, connected to each side of the central wall and to the shaking table through a steel support brace system. The configuration details are provided in Experimental activities section. All steel connection components, including base beams, anchorage assemblies, shear keys, dissipator connections, and inerter supports, were designed to remain elastic during testing to ensure stable and repeatable boundary conditions. Detailed geometrical properties, connection details, and technical drawings are provided in the accompanying dataset.