MIT-IIT Bombay

As a continuation of the ongoing research investigating the effect of the high frequency seismic vibrations on unreinforced masonry, a series of dynamic tests will be conducted on IIT Bombay's shake table.

SCOPE OF THE TESTS AT IITB

The main goal of the experimental research is to run a number of tests on IITB's shake table, with horizontal vibrations and variable frequency, to complement the tests conducted previously on a vibrating table, with vertical acceleration and fixed frequency (60Hz) at MIT.

SHAKE TABLE CHARACTERISTICS

The shake table in IITB's Heavy Structures Lab (Fig. 1) has the following characteristics:

- Dimensions: 1.2 x 1.2 m
- 1 DOF
- Maximum acceleration: 4g
- Maximum frequency: 35Hz
- Stroke: 0.1-110mm

TEST SETUP

The specimens will be aligned with the direction of motion of the shake table. The specimen dimensions will vary depending on the type of test of specimen, brick or stone, and the type of test.

Instrumentation

The displacement/acceleration of the 5 ton actuator will be set by the loading history. Additional accelerometers and LVDT will be installed on the shake table (Fig. 2) and on the top of the specimen.

Figure 1: Heavy Structures Lab

Figure 2: Test setup

SPECIMEN CHARACTERISTICS

Two types of URM wall specimens will be tested dynamically: brick masonry and stone masonry.

1. Brick specimen

The bricks used in the construction of the brick specimens (Fig.3) had to be specially ordered because the locally used bricks had a very deformed shape. These deformations can be corrected in a construction with mortar, but would significantly deform a dry masonry specimen. A gap of 110mm was left between the two brick wall leaves to introduce the 2/3" gravel infill. Two U-shaped steel members connected at the top were used as the lateral boundaries to restrain the infill laterally.

Fired brick dimensions:
Specimen dimensions:
1. Static: :
2. Dynamic test:

2. Stone specimen

Due to the fact that natural stones were difficult to obtain, the stones used in the construction of the stone specimens (Fig. 4) were of the quarry type. The construction of the specimen approximately followed the same process used in the construction of low-cost housing.

Specimen dimensions: (600x500x250)mm

Figure 3: UR Brick Wall

Figure 4: UR Stone Wall