A quite general base connection modeling capable of accurately representing material and geometrical nonlinear behavior of the base plate and arbitrary nonlinear contact with concrete foundation has been demonstrated and its implementation in a finite element nonlinear seismic analysis is presented. A time domain finite element methodology for nonlinear dynamic analysis problem that accounts for base connection lift-off and the inelastic behavior of anchor bolts through an incremental-iterative procedure is developed. A representative problem of cable-stayed bridges tower subjected to strong ground motion is analyzed. The maximum bearing stress on the concrete foundation as well as the tension force per anchor bolt that necessary to design the anchorage system is computed.

Strengthening and repairing of reinforced concrete beams by using thin fibers concrete jacket have many advantages such as increasing of ultimate load, enhancement of serviceability limit state, resistance to fire and avoiding of corrosion problems that appear in steel plate jacket. The present work conducted to study the strengthening and repairing of reinforced concrete beams subjected to short time repeated load by using mixed steel fibers concrete jacket (MSFCJ). For this purpose fourteen reinforced concrete beams have a cross section 120x300 mm, total length 2300 mm were fabricated and tested under three point load. The used concrete mix contains two mixed shape steel fibers, corrugated and end-hooked steel fibers. Two of these beams were fabricated without strengthening, the first was tested under static load up to failure and the second was tested under short time repeated loads up to failure. The rest twelve beams, six of them were strengthened by U-shape MSFCJ with various thickness and steel fibers content while the other six beams were loaded up to 0.5 the ultimate static load and then repaired using MSFCJ. The twelve beams were tested under short time repeated load. The tests results showed the effectiveness of the proposed technique in both ultimate and serviceability limit state.

Strengthening and repairing of reinforced concrete beams by using thin fibers concrete jacket have many advantages such as increasing of ultimate load, enhancement of serviceability limit state, resistance to fire and avoiding of corrosion problems that appear in steel plate jacket. The present work conducted to study the strengthening and repairing of reinforced concrete beams subjected to short time repeated load by using mixed steel fibers concrete jacket (MSFCJ). For this purpose fourteen reinforced concrete beams have a cross section 120x300 mm, total length 2300 mm were fabricated and tested under three point load. The used concrete mix contains two mixed shape steel fibers, corrugated and end-hooked steel fibers. Two of these beams were fabricated without strengthening, the first was tested under static load up to failure and the second was tested under short time repeated loads up to failure. The rest twelve beams, six of them were strengthened by U-shape MSFCJ with various thickness and steel fibers content while the other six beams were loaded up to 0.5 the ultimate static load and then repaired using MSFCJ. The twelve beams were tested under short time repeated load. The tests results showed the effectiveness of the proposed technique in both ultimate and serviceability limit state.

Strengthening and repairing of reinforced concrete beams by using thin fibers concrete jacket have many advantages such as increasing of ultimate load, enhancement of serviceability limit state, resistance to fire and avoiding of corrosion problems that appear in steel plate jacket. The present work conducted to study the strengthening and repairing of reinforced concrete beams subjected to short time repeated load by using mixed steel fibers concrete jacket (MSFCJ). For this purpose fourteen reinforced concrete beams have a cross section 120x300 mm, total length 2300 mm were fabricated and tested under three point load. The used concrete mix contains two mixed shape steel fibers, corrugated and end-hooked steel fibers. Two of these beams were fabricated without strengthening, the first was tested under static load up to failure and the second was tested under short time repeated loads up to failure. The rest twelve beams, six of them were strengthened by U-shape MSFCJ with various thickness and steel fibers content while the other six beams were loaded up to 0.5 the ultimate static load and then repaired using MSFCJ. The twelve beams were tested under short time repeated load. The tests results showed the effectiveness of the proposed technique in both ultimate and serviceability limit state.

Since the occurrence of the Cairo earthquake on October 1992, the design of structures for earthquakes became a major demand enforced in the Egyptian design codes. The seismic response of building structures can be estimated through utilization of a variety of analysis methods that range from simple equivalent static analysis to complex nonlinear dynamic analysis. The traditional approach is to employ equivalent static analysis methods, while current design practice is moving toward an increased emphasis on the nonlinear analysis method. The Egyptian code provisions for building seismic design adopt the traditional approach of equivalent static load method as the main method for evaluating seismic actions and recommend the response spectrum method for nonsymmetrical buildings. This study aims to evaluate the Egyptian code provisions for the seismic design of moment-resistant frame multi-story building through using nonlinear time history analysis. The analysis procedures are evaluated for their ability to predict deformation demands in terms of inter-story drifts, potential failure mechanisms and story shear force demands. The results of the analysis of the different approaches are used to evaluate the advantages, limitations, and ease of application of each approach for seismic analysis.

A nonlinear dynamic analysis, including soil-structure interaction, is developed to estimate the seismic response characteristics and to predict the earthquake response of cable-stayed bridge towers with spread foundation. An incremental iterative finite element technique is adopted for a more realistic dynamic analysis of nonlinear soil-foundation-superstructure interaction system under great-earthquake ground motion. Two different approaches to model soil foundation interaction are considered: nonlinear Winkler soil foundation model and linear lumped-parameter soil model. The numerical results show that the simplified lumped-parameter-model analysis provides a good prediction for the peak response, but it overestimates the acceleration response and underestimates the uplift force at the anchor between superstructure and pier. The soil bearing stress beneath the footing base is dramatically increased due to footing base uplift. The predominant contribution to the vertical response at footing base resulted from the massive foundation rocking rather than from the vertical excitation.

The seismic response of building structures can be estimated by several analysis methods. Each approach incorporates different assumptions and varies in complexity of application. The traditional approach is to employ equivalent static analysis methods while current design practice is moving towards an increased emphasis on nonlinear analysis methods. This study examined the seismic performance of multistory buildings designed according to Egyptian code. Nonlinear time history analysis is used for evaluation of equivalent static and response spectra procedures that recommended by Egyptian codes for seismic design of building structures. In this study, a preliminary seismic response analysis of two buildings was performed using three analysis procedures to evaluate the building seismic performance and the difference in global response predicted by the three methods. Moreover, three analysis procedures are evaluated for their ability to predict deformation demands in terms of inter-story drifts and potential failure mechanisms. Three ground motions of earthquake records are used for seismic demands evaluation of these buildings. The results demonstrated that, for the three analysis methods used in this study, different predictions of seismic response occurred. Furthermore, the results of the analyses are used to evaluate the advantages, limitations, and ease of application of each approach for seismic analysis. Each method is shown to have merits and deficiencies that should be considered when selecting a seismic analysis method for a particular building structure.