The purpose of this paper is to investigate analytically the fully grouted rock bolt interaction with grout and rock in pullout test and to determine the load-displacement curve of the bolt head (beginning of the bonded section). Usually, the pullout test output is only the load-displacement curve. This paper discusses how to use this curve to determine the bolt-grout-rock interaction. For modeling bolt-grout interface behavior, coupling (compete for bonding), partial decoupling, decoupling with the residual shear strength, and complete decoupling have been considered. With increasing the applied load, two possible cases including complete pullout and bolt shank yielding are considered. Based on experimental results, a model for the shear stress along a fully grouted bolt is assumed. According to this model, the distribution of axial stress in the bolt and displacement of the bolt head is determined. It is also assumed that the bolt is sufficiently long, which is usually used in underground excavations. Based on the presented analytical method, the bolt head load-displacement curve is determined by assuming input parameters. This curve is compared with a pullout test result.

Researchers have been long investigating modern constructional approaches to improve the efficiency and reliability of the constructs and decrease time, costs, and effort. One such modern constructional approach is the use of prefabricated modular construction forms. Broad sustainable building (BSB) is a modern prefabricate modular steel form with special connections. In this paper, we investigate the effects of the thickness of the connection plates, the use of stiffener with different dimensions, and the use of a pyramid-shaped section on the load-displacement curve under cyclic loading. We use the finite-element software "ABAQUS" to model the connections. For verification of the obtained results from the software has been checked by comparing them with experimental models. The obtained results indicate that 50% increment in the thickness of the connection plates causes an increment of approximately 7.56%, 1.51% and 19% in yielding force, the displacement at the beginning of the yielding, and maximum bearable force by the connection respectively. The obtained results also demonstrate that the connection has a good ductility such that most of the samples can bear a rotation of 0.70 radian without a decrease in the bearable load or a failure in the connection.

According to the vital role that bridges play in transportation system and also communications of a society, monitoring their structural safety and keeping theme in service is crucial. Numerous methods have been proposed for detecting probable damages in bridges. Unfortunately most of them are based on comparison between the response of bridge in an intact and damaged state. Therefore intact state response must be known. However, not always it’, s true in practice. So proposing a method which can determine and localize damages without prior knowledge of intact state is necessary. Such a method which was proposed by Sun et al. is studied carefully. Through the aforementioned method, the dynamic displacement response of a simply supported beam was decomposed into a dynamic component and a quasi-static component. Using Maxwell-Betti law of reciprocal deflection, the quasi-static component was attributed to the static deflection of the beam. Later damage which is defined by loss of stiffness, could be localized based on the abrupt changes in the static deflection curvature as it is related to bending moment and flexural stiffness of a beam. It is found out that the decomposition approach proposed by Sun et al. is restricted to fact that only one mode of oscillation must be dominant and also the natural frequency of motion must be determined through experimental measuring. Another limitation is that the abrupt changes in the curvature diagram cannot be related to damage essentially as curvature is also affected by the bending moment. In this study two modifications were proposed to get more accurate results in localizing the imposed damages. The first modification is the use of EMD method in order to decompose the displacement response into its intrinsic mode functions. Hence the aforementioned method could be used in real bridge displacement responses as higher modes corporations can also be determined and extracted through EMD process and finally the quasi-static component is determined as the residue of EMD algorithm. Also the ambient noise may be decomposed from the original signal, improving the method to work in real situations. The second modification is creating an imaginary constant moment length in the beam by the use of super position principle. So sudden increase in the curvature diagram is essentially a damage. Different scenarios of damage were studied and both methods have been used to detect damage in each scenario. Results show a great improvement in detection and localization of damage using the improved algorithm rather than the original proposed method. Eventually a five span real bridge model was taken into study. The improved damaged detection method could clearly determine the longitudinal position of the damage.

The ideal performance of seismic isolating systems during the past earthquakes has proved them to be very useful in protecting structures against earthquakes. The cyclic loading experimental tests are an important part in the process of completing the design of the isolators, yet they are very expensive and time consuming. Using the accurate analytical modeling of hysteresis tests and knowing the limitations and the amount of error of the finite elements model and its effect on designing the isolated structure make it possible to reduce the financial and time expenses involved in designing seismic isolators along with experimental tests. In the present study, the cyclic loading of two different isolating systems, namely, the high damping rubber bearing (HDRB) and lead rubber bearing (LRB) have been modeled and analyzed in ABAQUS and the outcomes were compared with the experimental results attained by other researchers. Regarding the fact that the most important and complicated component of the elastomeric isolating system is rubber, it was modeled using various strain energy functions. Other factors affecting the finite elements models of elastomeric isolators were also studied. After comparing the effective stiffness of the experimental sample with the analytical model of HDRB, the Yeoh function had the best performance in determining the effective stiffness of the isolating system with an error of less than 7%. In studying LRBs, too, three types of bearings with different dimensions and lateral strain values were studied; the polynomial function in shear strain value of 150% had the best performance in estimating effective stiffness and damping with errors of less than 3% and 18%, respectively.