This study attempts to optimize the prediction accuracy of the compressive strength of high-performance concrete (HPC) by comparing data-mining methods. Modeling the dynamics of HPC, which is a highly complex composite material, is extremely challenging. Concrete compressive strength is also a highly nonlinear function of ingredients. Several studies have independently shown that concrete strength is determined not only by the water-to-cement ratio but also by additive materials. The compressive strength of HPC is a function of all concrete content, including cement, fly ash, blast-furnace slag, water, superplasticizer, age, and coarse and fine aggregate. The quantitative analyses in this study were performed by using five different data-mining methods: two machine learning models (artificial neural networks and support vector machines), one statistical model (multiple regression), and two metaclassifier models (multiple additive regression trees and bagging regression trees). The methods were developed and tested against a data set derived from 17 concrete strength test laboratories. The cross-validation of unbiased estimates of the prediction models for performance comparison purposes indicated that multiple additive regression tree (MART) was superior in prediction accuracy, training time, and aversion to overfitting. Analytical results suggested that MART-based modeling is effective for predicting the compressive strength of varying HPC age.

Generally, in seismic retrofit design, seismic performance of a RC building can be upgraded to meet or exceed code requirements by upgrading the structural strength, ductility, or a combination of both. Except for safety, financial and environmental benefits of seismic retrofit investments are not considered in seismic retrofit design. However, financial and environmental benefits are very important information for decision making in seismic retrofit investments. In this work, a novel method for estimating seismic damage to an RC building is constructed based of the hazard curve of response spectral acceleration. Additionally, earthquakes are assumed to follow a Poisson process when analyzing the probability of a specified damage state within a specified service period and modeling expected costs caused by seismic damage. In addition to costs, CO2 emissions caused by seismic retrofit and repairs are considered the environmental impact when assessing payback periods of seismic retrofit investments ...

In this work, the piezoceramic-based transducers are used to perform the structural health monitoring (SHM) and interface damage detecting of non-ductile reinforced concrete (RC) frames retrofitted by post-installed RC walls. In order to develop the post-embedded piezoceramic-based transducers that can be used to identify interface failure or cracks between two structural members in retrofit construction, this work adopts the cyclic loading to test two specimens with post-embedded piezoceramic-based transducers (PPT). Since the failure of an interface between the post-installed wall and beam occurs, one of the specimens has damage in the foundation and existing boundary column and the other has damage in the top ends of column and wall. During the cyclic loading test, one transducer was used as an actuator to generate the stress waves and the other transducers were used as the sensors to detect the waves. In damaged specimens, the existence and locations of cracks and the interface damage can be detected by analyzing the wave response. Moreover, the severity of damage to the specimens can also be estimated. The experimental results indicate the effectiveness of the piezoceramic-based approach in the SHM and locating damage in shear-critical RC structural members under the seismic loading.

To quantify the post-earthquake residual seismic capacity of reinforced concrete (RC) column members, experimental data for 6 column specimens with flexural, flexural–shear and shear failure modes...

The purpose of this study is to investigate the flexural crack development of high-strength reinforced concrete (HSRC) beams and suggest the design equations of the flexural crack control for HSRC...