Journal of Seismology and Earthquake Engineering
Volume:26 Issue: 3, Summer 2024

Buried pipeline response to earthquake induced landslide is one of the challenging problems in geotechnical earthquake engineering. In this study, two physical models were constructed to investigate the effect of burial angle of the pipes on their response to the landslide. Similitude laws for 1g shake table tests were employed to construct the physical models. In each model, four aluminum pipes were installed at different positions but at identical depths from the model surface. All the properties in both models - except the pipes angles relative to the slope - are the same. The pipes were heavily instrumented with pair strain gauges to measure pure bending strain. Input shaking consisted of 25 sinusoidal cycles of loading with amplitude of 0.32 g and frequency of 5 Hz. The results showed that reduction of pipe burial angles from90 to 70 degrees in relative to the slope direction, decreased bending strain in the pipes. Therefore, reduction of burial angle of the pipes can be considered as one of the remediation methods against landslide. Also, in both models, the lower part of the slope was the most critical location for buried pipes

Lateral forces, especially seismic forces, cause significant damage to structures, especially tall ones. On the other hand, sequence earthquakes also cause irreparable damage to structures. Therefore, post-tensioned connections are one way to improve structures' seismic behavior. This study investigated 12-story tall steel structures with simple flexural connections and post-tensioned connections in two dimensions and 5- and 8-story structures with simple flexural connections and post-tensioned connections in two dimensions under sequences earthquakes. In this study, the beam and column sections of the sarees mentioned above were designed with ETABS software and simulated with OpenSees software to apply sequence records. The previous simulation was validated, and the structures were analyzed non-linearly under sequence records. The results indicated that the maximum drift angle was reduced by 50% in the 12-story structure with post-tensioned connections. As a result, post-tensioned connections improved the behavior of tall structures.

This study investigates cost-effective methods for retrofitting reinforced concrete joints using FRP (Fiber Reinforced Polymer) laminates and the NSM (Near-Surface Mounted) technique. Due to the high cost associated with preparing concrete surfaces and attaching FRP laminates, the study focuses on identifying optimal FRP strip configurations that minimize material use and surface preparation. Finite element modeling in ABAQUS revealed that a combined configuration of X-shape and orthogonal FRP strips achieves load-bearing capacities comparable to full FRP coverage, while reducing FRP material requirements by about 30%. Additionally, the study examined the performance of connections reinforced with FRP composites and CFRP rebars using numerical methods and laboratory results, assessing properties such as force-displacement curves, ductility, hardness, cracking, energy, and plastic strain. The findings demonstrate that the combined use of strip connections and the NSM method effectively enhances the structural performance of concrete beam-column joints, providing a practical and economical solution for seismic retrofitting

One of the methods to reduce damages caused by earthquakes is to concentrate damages in predetermined members. During an earthquake, these members minimize the damage caused to other members of the structure by absorbing a major part of the earthquake force. These members act like an electrical fuse that is blown under an unauthorized current of electricity and prevents damage to the wiring and electrical appliances used; Therefore, these members are called "structural fuse" and sometimes abbreviated as "fuse".EBFs are one of the most important resistant systems for bearing lateral loads. Researchers, paying attention to the simple replaceability approach, have introduced a shear fuse with joint connection in the connection area, which is named as a simple replaceable fuse. In this project, a series of numerical and laboratory researches are carried out in full scale, and this article refers to the comparison of design parameters.In this article, a brief explanation of Young's, Presley-Pauli's and energy methods is presented in each section, and then the design parameters are determined and compared. ETABS software was used for frame design and ABAQUS was used for numerical analysis. The comparison results show that the use of this fuse in EBFs has significantly improved the design parameters. Due to the simplicity of manufacturing and installing this fuse, using this method optimizes the design and saves the costs of construction and seismic improvement.

Modeling the nonlinear behavior of structural elements is one of the important parameters for assessing the fragility of steel moment frames. Nonlinearity modeling of structural components is done with two methods a) distributed plasticity, and b) concentrated plasticity. In distributed plasticity method, the element is considered fibrous and non-linear. In contrast, in concentrated plasticity method, the element is assumed to be elastic and the place of hinges formation is considered at its two ends. To investigate the effect of nonlinear modeling of structural elements on the fragility of steel moment frames a 6-story frame, which is optimally designed with RUPSO algorithm, is considered. The results show that the steel moment frame with concentrated nonlinearity is more fragile than the one with distributed nonlinearity.

Wavelet transforms have been used for 20 years to reduce dynamic analysis costs, with studies suggesting the use of this method for three levels of decomposition. In addition, in these studies, the time step of the solution is assumed to be equal to the time step of the earthquake record and therefore the stability of the numerical method is essential in such cases. Also, in previous studies, the effects of the distance from the fault on the accuracy of the approximate waves have not been evaluated. This paper examines the accuracy of wavelet-based down-sampling methods for 50 far-field, near-field, and pulse-like earthquake records and 24 wavelet functions. Also, two numerical methods, Newmark's average acceleration and the interpolation-based method are studied. The results of this research show that Newmark's average acceleration method is suitable for wavelet-based dynamic analysis. Also, in this study, it is shown that by choosing the appropriate wavelet function, even up to four levels of decomposition may be used with an error of less than 2%. Therefore, with this work, the cost of calculations may be reduced up to 16 times.