In the past few years, some experimental investigations have been conducted to verify seismic behaviour of fiber reinforced polymer reinforced concrete (FRP-RC) beam-column joints. Those researches were mainly focused on exterior beam-column joints without lateral beams. However, lateral beams, commonly exist in buildings, can significantly improve seismic performance of the joints. Moreover, the way the longitudinal beam bars are anchored in the joint, either using headed-end or bent bars, was not adequately addressed. This study aims to fill these gaps and investigate the shear capacity of FRP-RC exterior beam-column joints confined with lateral beams, and the effect of beam reinforcement anchorage on their seismic behaviour. Six full-scale exterior beam-column joints were constructed and tested to failure under reversal cyclic loading. Test results showed that the presence of lateral beams significantly increased the shear capacity of the joints. Moreover, replacing bent bars with headed-end bars resulted in more ductile behaviour of the joints.

In the past few years, some experimental investigations have been conducted to verify seismic behaviour of fiber reinforced polymer reinforced concrete (FRP-RC) beam-column joints. Those researches were mainly focused on exterior beam-column joints without lateral beams. However, lateral beams, commonly exist in buildings, can significantly improve seismic performance of the joints. Moreover, the way the longitudinal beam bars are anchored in the joint, either using headed-end or bent bars, was not adequately addressed. This study aims to fill these gaps and investigate the shear capacity of FRP-RC exterior beam-column joints confined with lateral beams, and the effect of beam reinforcement anchorage on their seismic behaviour. Six full-scale exterior beam-column joints were constructed and tested to failure under reversal cyclic loading. Test results showed that the presence of lateral beams significantly increased the shear capacity of the joints. Moreover, replacing bent bars with headed-end bars resulted in more ductile behaviour of the joints.

The recent earthquakes in Turkey have shown the poor seismic performance of reinforced concrete. This led to widespread utilization of several strengthening methods, each of which is convenient in different aspects. However, what is required to apply any of these methods is to evacuate the building in question since the interruptions are mostly within the building and to the structural members. This study proposes a method for external strengthening of typical five storey reinforced concrete buildings that represent the majority of the built environment in Turkey. The method suggests addition of shear walls, which are connected to each other by means of diaphragms on two floor levels, to the existing external columns at four corners of the building. The positive effect of shear walls in seismic performance is already known / however / basically, the aim of this study is to discuss the feasibility of the proposed method in terms of architectural viewpoint since the method unavoidably covers great modifications on the architectural form of the building. Hence, the research mostly explores whether it is possible to give the reinforced concrete residential buildings, which constitute the majority of the built environment especially after 1950s due to the unhealthy urbanization period in Turkey, a common characteristic appearance by means of external structural members. As a whole, proposing an external strengthening method that provides not to evacuate the space, the study searches to obtain a typical fa&ccedil / ade resemblance by means of additional structural members.

Στόχος της εργασίας είναι η παραμετρική μελέτη μεταλλικών τρισδιάστατων πλαισίων με συνδέσμους δυσκαμψίας, ανθεκτικούς σε λυγισμό (BRB: Buckling Restrained Braces). Τα πρώτα κεφάλαια της εργασίας αποτελούν το θεωρητικό υπόβαθρο της διατριβής και αναφέρονται στα ζητήματα που αφορούν τον αντισεισμικό σχεδιασμό των μεταλλικών κατασκευών. Στο υπόβαθρο αυτό βασίστηκε τόσο ο σχεδιασμός του δείγματος των κατασκευών όσο και η επιλογή των υπό διερεύνηση παραμέτρων. Το αντικείμενο της εργασίας καθαυτό παρουσιάζεται στα τρία τελευταία κεφάλαια όπου γίνεται η περιγραφή του σχεδιασμού των τελικών κτιρίων ώστε να επιτευχθεί φυσική μονοαξονική εκκεντρότητα και στη συνέχεια η ανάλυση των κατασκευών αυτών με μη γραμμικές αναλύσεις. Από αυτές δημιουργείται μια βάση δεδομένων από την οποία εξάγονται συμπεράσματα που αφορούν τη συσχέτιση της εκκεντρότητας με τα μεγέθη απόκρισης των κατασκευών. / The subject of this thesis is the non linear analysis of 3D steel frames with buckling restrained braces (BRB).

A reliability-based criterion to estimate strength amplification factors for buildings with asymmetric yielding located within a seismic region presenting different soil conditions is proposed and applied. The approach involves the calculation of the mean annual rate of exceedance of structural demands of systems with different levels of asymmetric yielding. Two simplified mathematical expressions are developed considering different soil conditions of the valley of Mexico. The mathematical expressions depend on the ductility of the structural systems, their level of asymmetric yielding, their fundamental vibration period and the dominant period of the soil. In addition, the proposed expressions are compared with that recommended by the current Mexico City Building Code (MCBC). Since the expressions are developed with the help of simplified structural systems, the validity of such expressions is corroborated by comparing the expected ductility demand of multi-degree of freedom (MDOF) structural systems with respect to that of their equivalent simplified systems. Both structural representations are associated with a given annual rate of exceedance value of an engineering demand parameter. The expressions proposed in this study will be incorporated in the new version of the MCBC.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16821号 / 工博第3542号 / 新制||工||1535(附属図書館) / 29496 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 小池 武, 教授 竹脇 出, 准教授 五十嵐 晃 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17137号 / 工博第3627号 / 新制||工||1551(附属図書館) / 29876 / 京都大学大学院工学研究科都市社会工学専攻 / (主査）教授 小池 武, 教授 杉浦 邦征, 准教授 五十嵐 晃 / 学位規則第4条第1項該当

<div>The author aims to investigate the current design provision for seismic and foundation settlement design of aboveground open-top storage tanks using finite element analysis. The thesis is divided into two independent but closely related studies: (1) seismic analysis of open-top storage tanks with flexible foundation and (2) fitness-for-service of open-top storage tanks subjected to differential settlement.</div><div><br></div><div>The present seismic design provisions in American Petroleum Institute’s storage tank standard API 650 (2013) assumes the tank foundation is rigid and therefore, ignores the effect of uplift during a seismic excitation. In the first study, the objective was to quantitatively critique rigid foundation assumption and conclude if the assumption is acceptable or not for a given tank geometry. Tanks with three different height to diameter ratio (H/D), i.e aspect ratios, of 0.67, 1.0 and 3.0 representing broad, nominal and slender geometry, respectively, were modelled having both rigid and flexible foundations. The flexible foundation was modelled with series of non-linear compression only springs. Additionally, for each tank model two different hydrodynamic pressure distribution suggested by (1) Housner and (2) Jacobsen-Veletsos were applied which are used by API 650 and Eurocode 8, respectively. Geometric non-linear analysis with non-linear material properties was conducted (GMNA) using Riks algorithm in Abaqus finite element analysis (FEA) program. The hoop stresses, longitudinal stresses, uplift and buckling capacity of each rigid foundation tank model were compared with its respective flexible foundation tank model and corresponding API 650 rule based provisions. It was observed that the assumption of rigid foundation from design point of view is acceptable for the broad tank, however, for the nominal and slender tanks this assumption is not acceptable. The buckling capacity of nominal and slender tanks having flexible foundation are significantly lower compared to rigid foundation. Therefore, the effect of uplift should not be neglected for design purposes for nominal and slender tank geometries.</div><div><br></div><div>In the second study, an alternative method for evaluating the structural integrity of storage tank subjected to differential settlement is proposed. The limitations of the existing method in API 653 (2014), currently used in the industry are highlighted. The tank settlement is measured underneath</div><div>12</div><div>the tank bottom along the tank circumference at discrete locations. The settlement can be transformed into a Fourier series by combining different harmonic components. In the existing API 653 method there is no distinction between the effects of different harmonic components whereas in the proposed method the effects of first five harmonic components are individually accounted and the cumulative damage is evaluated. The proposed method is formulated based on FEA conducted on twenty-one different tank models with each having different tank geometry. The limiting settlement value for each harmonic wave number is found for a given tank geometry by conducting GMNA using Riks algorithm, and a generalized trend is found for each harmonic wave number. The proposed method is further validated by performing numerous FEA simulations. The simulations were conducted for several tank models subjected to four representative actual measured settlement data. A set of tank models used in the validation was generated using random tank geometries and design parameters to have a blind test of the proposed method. Finally, a comparison is made between allowable settlement based on the API 653 method, the proposed method and the FEA. It was observed that the proposed method consistently results in conservative results compared to FEA. In contrast the API 653 method does not always result in conservative results. For some measured settlement data, the API 653 method gives overly conservative values and for others it gives non-conservative values. Moreover, the API 653 method is based on the beam theory which may not capture the true shell behavior. Therefore, the API 653 method requires modifications. The proposed method on the other hand is consistent and is based FEA which can capture the true shell behavior as it is formulated using shell theory. Therefore, it is recommended that the existing method in API 653 shall be replaced with the proposed method to determine the fitness of tank under differential settlement.</div>

Steel special moment frames (SMFs) are known to be highly ductile seismic force- resisting systems. The performance of an SMF relies on the ability of the connections to accommodate large inelastic deformations. After the brittle failure of some steel moment frame connections during the 1994 Northridge Earthquake, experimental tests were used to investigate the ductility and strength of these connections. An experimental study was performed to investigate the seismic performance a new connection called the Replaceable Shear Fuse (RSF) connection. The RSF connection uses shear-yielding fuse plates to prevent beam and column yielding. A total of 7 test specimens with varying fuse plate sizes and configurations, a W14×48 column, and a W14×38 beam were created. The connections were loaded laterally and cyclically at increasing displacements until the connection failed. The results show that RSF connections have the capability to prevent beam and column damage by focusing inelastic rotations to shear fuse yielding and bolt slip. Specimens with 14 in. deep beams achieved rotations ranging from 0.06 to 0.10 rad without excessive degradation and local buckling. Stable yielding was also achieved for all test specimens. Hysteretic responses for Specimens A1.3 and A1.4 were similar to typical responses from welded moment connections. The behavior of Specimen A1.16 was similar to that of a bolted flange plate connection, whereas the other remaining specimens had responses that were a combination of welded moment and bolted flange plate connections. Peak responses from tests indicated that inelastic rotations were accommodated by both fuse plate yielding and bolt slip. The first observation of major bolt slip occurred in the fuse plates as early as the 0.05 rad drift cycle. The early occurrence of bolt slip allowed for a higher rotational capacity. While the top and bottom fuse plates were replaced for each test, no repairs were needed for the beam and column. The RSF connection proved to be a more resilient alternative SMF connection.

An ultra-lightweight buckling-restrained brace (ULWBRB) is developed using a highly ductile aluminum core and FRP restrainer. Utilization of lightweight materials results in a BRB that is 25% the weight of traditional mortar-filled tube varieties allowing easy installation in small to medium sized buildings requiring seismic retrofit without the need for heavy equipment. Construction utilizes commonly stocked materials able to be customized for required strength, drift, and geometry limitations. Analytical single degree of freedom (SDOF) and Euler buckling models are compared with published equations to determine the required restrainer stiffness (RRS). SDOF models yield RRS values 200% higher than the Euler model. Applied end moments due to frame deformation are incorporated into a modified design method that gives RRS values 50% higher than Euler model without eccentricity. RRS is provided using a bundled and wrapped FRP tube configuration using a developed shear flow method considering composite action. Uniaxial low-cycle fatigue (LCF) testing of a 6061-T6 candidate alloy provides data for a constitutive model using combined kinematic-isotropic hardening. LCF testing of round short gage coupons indicates the candidate alloy is capable of stable cycling to 2%, 3%, and 4% total strain with excellent ductility. Early fracture of specimens at 24, 18, and 11 cycles, respectively, also indicates that other candidate alloys should be examined for improved fatigue life. However, inconsistency is noted between similar tests of 6061-T6 that were able to achieve up to 76 cycles at 2.5% total strain. ULWBRB FEA models loaded monotonically consistently give higher RRS values as compared to the analytical methods. This is due to assignment of initial imperfections, longer more realistic unbraced length, higher axial loads achieved through the post-yield region, and plastic hinging potential. Cyclic simulations of braces with the same RRS values are also able to achieve reliable and stable hysteretic behavior through 21 cycles. If a less stiff restrainer is used, cumulative energy dissipation potential is reduced considerably due to pinched hysteresis loops and strain ratcheting. Applied end moments are found to have a linear effect on the RRS that can be modeled by superposition of the buckling effect plus end moment.