Monday, July 27, 2009

Collapse of a Building in Shanghai

"A 13-story under construction apartment building in Shanghai's Lotus Riverside complex fell to its side on June 27, 2009. During construction, a 4.6-meter-deep underground garage was dug on the south side of the building while a mound of soil heaped up to 10 meters high was located on the other side. This caused a difference in pressure on two sites of the building, which resulted in the collapse of a building in Shanghai" according to the China Daily. The lateral pressure caused the piles to snapped resulting in the foundation failure and tilting of the building.

Wednesday, July 15, 2009

Learning Lessons: The 1990 Luzon Earthquake

On July 16, 1990, an earthquake with magnitude 7.8 struck central Luzon. The human consequences were severe - at least 1200 people were killed and more the 3000 injured. Major destruction occured in Baguio City where hotels and school buildings collapsed like pancakes and Dagupan city where extensive liquefaction caused settlement of buildings and bridges. What lessons can we learn from this earthquake? This video - part of the "Understanding Earthquakes and Disasters: Photo-Video Presentations" highlights some lessons from the 1990 Luzon Earthquake. This video can also be viewed (full screen) and downloaded at YouTube.
video

Thursday, July 9, 2009

A Neural Network Model for Confined RC Column

Artificial Neural Networks (ANN) are information – processing systems whose architecture mimic the biological system of the brain. Recently, civil engineers have utilized ANN for various applications especially in the modeling of civil engineering systems.

In my case, I developed an ANN model for predicting the confined compressive strength and strain of a circular reinforced concrete column. The model has seven input nodes: (1) unconfined concrete cylinder strength, f’c; (2) concrete core diameter, d, where the core is the part of the section enclosed by the centroidal axis of the hoop or ties; (3) column height, H; (4) yield strength of lateral reinforcement, fyh; (5) volumetric ratio of lateral reinforcement; (6) tie spacing, s ; and (7) vertical steel or longitudinal reinforcement ratio. The two output nodes, on the other hand, represent the peak stress or compressive strength of confined concrete circular column, f’cc and the strain, ecc , at peak stress. Shown below is the GUI of the Visual Basic program of the ANN model.
The predictions of the compressive strength or peak stress, f’cc, of confined concrete columns and the corresponding strain, ecc, have been a subject of various researches, both analytical and experimental. The values of these two parameters are usually used in the analytical models developed for describing the stress-strain relationship for confined concrete.

You may run the ANN model at http://mysite.dlsu.edu.ph/faculty/oretaa. Go to the Software section. Papers on the model can also be downloaded from this site.