Structural Response Prediction for Damage Identification Using Wavelet Spectra in Convolutional Neural Network

If damage to a building caused by an earthquake is not detected immediately, the opportunity to decide on quick action, such as evacuating the building, is lost. For this reason, it is necessary to develop modern technologies that can quickly obtain the structural safety condition of buildings after an earthquake in order to resume economic and social activities and mitigate future damage by aftershocks. A methodology for the prediction of damage identification is proposed in this study. Using the wavelet spectrum of the absolute acceleration record measured by a single accelerometer located on the upper floor of a building as input data, a CNN model is trained to predict the damage information of the building. The maximum ductility factor, inter-story drift ratio, and maximum response acceleration of each floor are predicted as the damage information, and their accuracy is verified by comparing with the results of seismic response analysis using actual earthquakes. Finally, when an earthquake occurs, the proposed methodology enables immediate action by revealing the damage status of the building from the accelerometer observation records.

Seismic Damage Assessment of Deficient Reinforced Concrete Frame Structures

In order to assess the seismic damage response of reinforced concrete deficient, weak beam-column connection frame structures, this study presents experimental shake table testing on representative 1/3rd reduced size and double story frame models. Two test models were considered for experimental testing, including a reference code design specimen and another frame with a similar characteristic, but was not provided with any shear reinforcement in the critical joint connection region and, was constructed with concrete having a compressive strength of 33 % less than the code specified value. The input scaled excitations were applied from 5 % to 130 % of the maximum input peak ground acceleration record, to deformed the test models from elastic to inelastic stage and then to fully plastic incipient collapse stage. The weak beam-column frame sustained plastic hinging at column bases and beam ends, with longitudinal reinforcement bar-slip and severe damageability of the joint panels upon subjected to multiple dynamic excitations. The deficient frame model was only able to resist 40 % of the maximum acceleration record as compared to the code design frame which was able to resist about 130 %.

SLAMMING IMPACT ACCELERATIONS ANALYSIS ON SMALL HIGH SPEED PASSENGER CRAFTS

Small high speed passenger crafts (HSC) are commonly known for their poor seakeeping qualities. These crafts are frequently exposed to large slamming impacts and these repetitive shocks may pose danger to passengers’ safety and health. In Malaysia, small high speed passenger crafts having lengths between 7 to 9 meters are mainly used to transport tourists between popular island destinations. Evaluation on impact and vibration for this type of craft was conducted by using accelerometers attached to several locations on craft’s deck. The test was conducted at speeds ranged between 20 to 30 knots and the highest peak accelerations were recorded. The highest acceleration record during the sea trial was recorded at 4.22 g and the average acceleration measure is 2.20 g. Apart from this test, evaluation on effectiveness of the current foam seat typically used in this craft were evaluated using Dynamic Response Index (DRI) and results have shown that the seat is less efficient when impact reaches more than 1g at speeds of more than 20 knots. It is concluded that safety measures such as the use of more efficient suspension seat and limiting the operational speed need to be taken into consideration.

Measuring and maintaining acceleration records obtained from 3D MEMS

Tracing or tracking of an object or a link is needed in many engineering applications. Achieving it in real time applications using MEMS or the traditional accelerometers is also a well-known method. Measuring acceleration in [3] directions is needed in handling equipment, material transfer and in manufacturing industry.In this work, Calibration of accelerometer sensor ADXL335 is carried out first to show the accurate values of „g‟. Then, the measurement of acceleration is carried out as per the code written in Arduino IDE. ADXL335 is interfaced with NODE MCU. NODE MCU uses HTTP protocol to send the measured acceleration values to cloud platform. ThingSpeak is the cloud platform chosen for this purpose. ThingSpeak requires selection of a number of fields. Here we have three values to be taken to cloud (X, Y and Z directions).For display purposes a mobile is used in conjunction with MIT App Inventor. Acceleration record files can be obtained that may be processed further. The application contains three buttons forward, side and vertical which displays the acceleration values across X, Y and Z directions respectively. The acceleration values are further integrated to obtain velocity and displacement .It can be done through 2 ways like ana- log integration and digital integration. But the analog integration is reliable only to measure the sinusoidal steady state values. So the digital integration is much better for obtaining a displacement signal from acceleration. It is possible to use these components for further processing and applications like ultrasonic applications, military devices namely mixers, elevators, mechanically handling equipment‟s and information handling devices like iPad, phones etc.

Rocking Behaviour of Multi-Block Columns Subjected to Pulse-Type Ground Motion Accelerations

Ancient columns, made with a variety of materials such as marble, granite, stone or masonry are an important part of the European cultural heritage. In particular columns of ancient temples in Greece and Sicily which support only the architrave are characterized by small axial load values. This feature together with the slenderness typical of these structural members clearly highlights as the evaluation of the rocking behaviour is a key aspect of their safety assessment and maintenance. It has to be noted that the rocking response of rectangular cross-sectional columns modelled as monolithic rigid elements, has been widely investigated since the first theoretical study carried out by Housner (1963). However, the assumption of monolithic member, although being widely used and accepted for practical engineering applications, is not valid for more complex systems such as multi-block columns made of stacked stone blocks, with or without mortar beds. In these cases, in fact, a correct analysis of the system should consider rocking and sliding phenomena between the individual blocks of the structure. Due to the high non-linearity of the problem, the evaluation of the dynamic behaviour of multi-block columns has been mostly studied in the literature using a numerical approach such as the Discrete Element Method (DEM). This paper presents an introductory study about a proposed analytical-numerical approach for analysing the rocking behaviour of multi-block columns subjected to a sine-pulse type ground motion. Based on the approach proposed by Spanoset al.(2001) for a system made of two rigid blocks, the Eulero-Lagrange method to obtain the motion equations of the system is discussed and numerical applications are performed with case studies reported in the literature and with a real acceleration record. The rocking response of single block and multi-block columns is compared and considerations are made about the overturning conditions and on the effect of forcing function’s frequency.