Dynamics of structures

Seismic Rehabilitation of Existing Buildings

The primary objective of this paper is to present a general review of the different macromodels used for the analysis of infilled frames. A number of distinct approaches in the field of analysis of infilled frames since the mid-1950s have yielded several analytical models. These studies stressed that the numerical simulation of infilled frames is difficult and generally unreliable because of the very large number of parameters to be taken into account and the magnitude of the uncertainties associated with most of them. In this paper, the advantages and disadvantages of each macromodel are pointed out, and practical recommendations for the implementation of the different models are indicated.

/pdf/mathematical-macromodeling-of-infilled-frames-state-of-the-4o1c4mvbob.pdf

Mathematical Macromodeling of Infilled Frames: State of the Art

Research and practice on progressive collapse and robustness of building structures in the 21st century

Mechanical behavior of concrete-filled square steel tube with FRP-confined concrete core subjected to axial compression

Masonry infill panels in framed structures have been long known to affect strength, stiffness, and ductility of the composite structure. In seismic areas, ignoring the composite action is not always on the safe side, since the interaction between the panel and the frame under lateral loads dramatically changes the stiffness and the dynamic characteristics of the composite structure, and hence, its response to seismic loads. This study presents a simple method of estimating the stiffness and the lateral load capacity of concrete masonry-infilled steel frames (CMISFs) failing in corner crushing mode, as well as the internal forces in the steel frame members. In this method, each masonry panel is replaced by three struts with force-deformation characteristics based on the orthotropic behavior of the masonry infill. A simplified steel frame model is also presented based on the documented modes of failure of the CMISF. The method can be easily computerized and included in nonlinear analysis and design of three...

Three-strut model for concrete masonry-infilled steel frames

Projects delays are among the most pressing challenges faced by the construction sector attributed to the sector’s complexity and its inherent delay risk sources’ interdependence. Machine l...

Machine Learning Algorithms for Construction Projects Delay Risk Prediction

Testing and modeling of a novel FRP-encased steel–concrete composite column

In this paper, the possibility of achieving a high level of ductility by flexural yielding in fully grouted reinforced concrete masonry shear walls is evaluated. Six full-scale walls were tested to failure under reversed cyclic lateral loading to investigate the effects of amount and distribution of vertical reinforcement and the level of axial compressive stress on the inelastic behavior and ductility. Results showed that yielding of the outermost vertical bars extended to a height equivalent to half the wall length. Also, the top wall displacement (drift) at the onset of yielding of the vertical reinforcement was highly dependent on the amount of reinforcement, but only minimally affected by the level of axial compressive load. However, at maximum loads, the displacements were less sensitive to either the amount of vertical reinforcement or the level of axial compression. Correspondingly, the displacement ductility was found to be very sensitive to the amount of vertical reinforcement, but was not dependent on the level of axial compression. In general, high levels of ductility and energy dissipation capabilities accompanied by relatively small strength degradation were observed for the test specimens.

Behavior of Fully Grouted Reinforced Concrete Masonry Shear Walls Failing in Flexure : Experimental Results

Composite materials are becoming more affordable and widely used for retrofitting, rehabilitating and repairing reinforced concrete structures designed and constructed under older specifications. However, the mechanical properties and long-term durability of composite materials may degrade severely in the presence of water intrusion. This study presents a new non-destructive evaluation (NDE) technique for detecting the water intrusion in composite structures by evaluating the dielectric properties of different composite system constituent materials. The variation in the dielectric signatures was employed to design a coplanar capacitance sensor with high sensitivity to detect such defects. An analytical model was used to study the effect of the sensor geometry on the output signal and to optimize sensor design. A finite element model was developed to validate analytical results and to evaluate other sensor design-related parameters. Experimental testing of a concrete specimen wrapped with composite laminate and containing a series of pre-induced water intrusion defects was conducted in order to validate the concept of the new technique. Experimental data showed excellent agreement with the finite element model predictions and confirmed sensor performance.

https://iopscience.iop.org/article/10.1088/0957-0233/19/7/075702/pdf

Wael El-Dakhakhni

Papers

Three-strut model for concrete masonry-infilled steel frames

Machine Learning Algorithms for Construction Projects Delay Risk Prediction

Testing and modeling of a novel FRP-encased steel–concrete composite column

Behavior of Fully Grouted Reinforced Concrete Masonry Shear Walls Failing in Flexure : Experimental Results

Coplanar capacitance sensors for detecting water intrusion in composite structures