Other Test Set-ups

In the laboratory of Semnan University, Iran, the test set-up shown in Figure 2.14was used to determine the effect of openings in masonry walls when subjected to in-plane shear loads. Built in a rigid steel frame, the wall specimen was subjected to lateral cyclic loading which was applied by means of two hydraulic jacks located on top and on the two sides of the specimen in a displacement controlled manner. A third hydraulic jack, positioned at the top of the specimen, applied a static axial load. All the loads were applied through a rigid steel beam placed on top of the wall (Karimi et al.,2016).

The displacements induced by the two horizontal hydraulic jacks were monitored through two linear variable displacement transducers (LVDTs), one placed by each horizontal hydraulic jack. The loads were measured by means of load cells which were placed between the specimen and the loading frame. The frame was securely attached to the laboratory floor and lateral bracings were utilized to prevent any out-of-plane movements of the specimens (Karimi et al.,2016). To assess the behaviour and the shear strength of ancient Italian brick masonry, the set-up shown in Figure2.15 was used to perform experimental tests on wall specimens made with the above-mentioned brick masonry. The walls were constructed and tested in a special loading frame fitted with three independent hydraulic jacks, two of which were used to apply the vertical loads, and the third, the monotonic horizontal load. Three load-cells were used to monitor the loads applied by the three jacks (Capozucca and Sinha,2004).

Each wall specimen was built with a flange on one side of the wall (T-shaped wall) and a steel plate glued with epoxy resin which was used as a slab at the top of the wall. The flange was made with mortar due to the scarcity of ancient bricks. Once the full pre-compression load was applied to the flange and the top of the wall, the shear force was then applied in stages until failure of the specimen (Capozucca and Sinha,2004).

Figure 2.14: Semnan University Test Set-up (Karimi et al.,2016)

Figure 2.15: Test Set-up with Loading Frame (Capozucca and Sinha,2004)

The test set-up from Key Laboratory of RC&PC Structures of the Ministry of Education – Southeast University – China, shown in Figure 2.16, was used to test self-insulating concrete masonry shear walls under in-plane cyclic loading. Each wall specimen was reinforced with steel bars and built on a foundation beam anchored to the laboratory floor. The axial load was applied by the vertical jack, connected to the crossbeam of a steel frame, and kept constant throughout the test. The horizontal cyclic loads were applied by the horizontal hydraulic actuator which was mounted to a reaction wall (Mohamad and Chen,2017).

Strong Floor Reaction Wall Hydraulic Actuator (500kN, ± 250mm) Wall Foundation Beam Ground Anchor Bolt Steel Bracing Wall Loading Beam Threaded Rod Vertical Jack Roller Bearing Frame Crossbeam

With the vertical reinforcement of the wall anchored in both the foundation and loading beams, each wall was designed to have reinforcements that ensured that the nominal shear strength of the wall was greater than the nominal flexural strength. The failure mode sought here was flexural failure as opposed to shear failure (Mohamad and Chen,2017). In the case of reinforced masonry shear walls, researchers (e.g.Mohamad and Chen,2017;Voon and Ingham,2006) have stated that flexural failure is the preferred failure mode as it is characterised by a ductile behaviour of the wall specimen and an effective energy dissipation through reinforcement yielding.

Once the vertical load was fully applied and maintained constant, the horizontal cyclic load was then applied in two steps; first in a force controlled manner until the yielding of flexural reinforcement, and then in a displacement control until failure of the specimen. The loads were applied through a loading beam whose lateral stability was achieved by means of transverse rollers (Mohamad and Chen,2017).

The test set-up shown in Figure 2.17was used by Haach et al.(2009) to perfom in-plane static cyclic tests on reinforced concrete block masonry walls. These tests aimed at contributing further to the knowledge gained on the performance of reinforced masonry walls and the influence of the added horizontal and vertical reinforcement when the walls are subjected to seismic actions. Each masonry wall specimen was built with horizontal and vertical reinforcement as well as reinforced concrete beams placed at the top and bottom of the wall. The vertical reinforcement were anchored in the concrete beams to ensure uniform distribution of the applied loads. To avoid uplift of the wall base, the bottom concrete beam was fixed to steel beams through steel bolts. Two adjustable clamping angles were used on each side of the concrete beam to prevent slippage of the specimen. The steel beams were connected to the strong floor through steel rods. The vertical load was applied by means of an actuator with vertical steel cables anchored at the strong floor. The load was then distributed at the wall top through a stiff steel beam and a set of steel rollers allowing displacement of the wall with respect to the vertical actuator. The horizontal load was applied with another actuator and transmited to the wall by means of two steel plates attached to the top concrete beam.