The low strength concrete are prevalent in many old buildings and common in current detailing practice in regions of lower seismicity [1]. This type of concrete is believed to generally exist in many developing country where the quality of design and construction material are very poor. The collapse of such low strength concrete under earthquake could be found in much country. For example, in 2008 Wenchuan earthquake, many buildings in Sichuan with poor quality concrete [2] were seriously damage and collapse under the earthquake. For example, in 2008 Wenchuan earthquake, many