Traffic induced vibration

Floor/Building Vibration

Building vibration caused by road traffic

In one case undertaken by RE, heavy-road-traffic-induced vibration caused a 5-story building to vibrate and shake. The building is located on the soft soil layer of the Chao Phraya River basin, which lowers stiffness. Also, damping amplifies the vibration.

In the testing process, real-time acceleration was monitored on each floor using accelerometers. The building was evaluated using the human comfort level, the floor acceleration guidelines and criteria as well as floor drift and building drift in general.

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Measurement of floor vibration caused by machines operation

Floor/Building Vibration

Floor vibration due to machines operations

In one case undertaken by RE, it was found that machine vibrations during the operations caused strong vibrations to the floor underneath. Thus, accelerometers were used to capture real-time floor and machine vibrations for all axes. Further, floor acceleration was double-integrated to floor dynamic displacement, as well as floor static displacement due to static floor self-weight, machine weight and floor live load, carried out by FEM programming to determine total floor displacement. Consequently, the floor safety was assessed.

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Vibration Measurement and Dynamic Structural Analysis

Floor/Building Vibration

Steel structure vibration due to machines

Large machine operations can cause vibration to the supporting platforms as well as the sheltering structures. Vibration is measured, and evaluation is made accordingly. In an example case of this, undertaken by RE, when the machines in the premises started operating, strong vibration was observed in the sheltering structure, and large deformation was visualized in long-slender steel columns. The reason was found to be an accidentally matching between machine vibration frequency and 1st natural frequency of the columns. Resonance therefore occurred.

In order to solve this problem, vibration measurement was conducted through an accelerometer and a dynamic data acquisition system. Data was then analyzed to determine machine vibration frequency and column displacement. The vibration measurement was done at various locations: the machine platform, the base of the column, the column at machine level and the column at the top level. The results showed that, even with the machine vibration at just 0.035g, the column vibration reached 0.1755g. This thus caused the column and siding walls to shake horizontally. Large out-of-plane column deformation was interpreted from the acceleration data to be 0.4 cm, exactly the same as that obtained from visual observation. Slenderness ratio of column in the out-of-plane direction was greater than recommended value stated in the codes of practice for steel design. SOLUTIONS were then GIVEN, and PROBLEMS are SOLVED.

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Water permability and concrete carbonation test

Structural Health Assessment

Concrete permeability is to determine how quickly oxygen, water and chloride ions will reach the layers of steel embedded in concrete, resulting in deterioration from reinforcement corrosion, carbonation, alkali-aggregate reaction, spalling of concrete, water leaking etc. Concrete cylindrical specimens were cored from a water storage structure, then the permeability test was conducted to determine the depth of water penetration and evaluate the water resistance ability as well as the life lasting of the existing structure.
Similarly, due to the presence of water, atmospheric CO2, they will result in the deterioration of protective film around the steels, allow corrosion to take place. Thus, carbonation test was performed to determine the level of degree of carbonation to estimate the remaining life of the structure.

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