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Open Access Publications from the University of California

Scholarly Works (8 results)

  • Article
  • Peer Reviewed
UC San Diego Previously Published Works (2022)
    Cover page: Force-Based Design Method for Force-Limiting Deformable Connections in Earthquake-Resistant BuildingsCreative Commons 'BY' version 4.0 license
    • Thesis
    • Peer Reviewed
    UC San Diego Electronic Theses and Dissertations (2022)

    This thesis studies the seismic response of an eighteen-story core wall building with force-limiting connections and low-damage coupling beams. Force-limiting connections allow the movement of the gravity load resisting system (GLRS) relative to the seismic force-resisting system (SFRS) and control the seismic-induced horizontal forces transferred between the two systems. Past research developed force-limiting connections that consist of a friction device or a buckling-restrained brace along with low-damping rubber bearings for buildings with planar SFRS with flexural inelastic base mechanism or rocking base mechanism. This thesis considers a force-limiting connection modified to accommodate the three-dimensional kinematic requirements between the GLRS and the SFRS in a reinforced concrete core wall building. The discrete variable limiting force is a novel characteristic in the force-displacement response of the modified force-limiting connection. Low-damage coupling beams, which consist of steel coupling beams with rotational friction connection ends, provide controlled moments with nonlinear responses concentrated on the rotational friction connections. Three-dimensional earthquake numerical simulations of an eighteen-story core wall building with modified force-limiting connections and low-damage coupling beams are performed. The use of modified force-limiting connections reduces the magnitude and the variability of the seismic-induced shear force, torsional moment, and acceleration responses of the building compared to the conventional core wall building with monolithic connections between the GLRS and the SFRS of the building while maintaining a reasonable connection deformation. The use of low-damage coupling beams instead of reinforced coupling beams could potentially reduce the coupling beam damage to accelerate the post-earthquake functional recovery of the building.

      Cover page: Seismic Response of Eighteen-story Core Wall Building with Force-limiting Connections and Low-damage Coupling Beams
      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2024)
      Abstract: This paper assesses the effects of (1) the gravity load‐resisting system (GLRS) modeling approach, (2) the seismic force‐resisting system (SFRS) modeling approach, and (3) the uncertainty of the model parameters of the constitutive law of the longitudinal reinforcing steel of the SFRS on the seismic responses of a 12‐story reinforced concrete wall building with force‐limiting connections. This is achieved by conducting nonlinear numerical earthquake simulations. The seismic responses of the building models with force‐limiting connections using two GLRS modeling approaches, (1) a moment frame system and (2) a pin‐base lean‐on‐column system, are compared. The seismic responses of the building models with conventional connections and force‐limiting connections, respectively, using two SFRS modeling approaches, (1) a distributed‐plasticity modeling approach and (2) a lumped‐plasticity modeling approach, are compared. A joint probability density function for the ASTM‐A615 Grade 60 steel available in the literature is used to conduct an uncertainty propagation analysis through Monte Carlo simulation. The uncertainty in the steel model parameters is propagated to the seismic responses of the building models with conventional connections and force‐limiting connections, respectively. The distributions of the mean values of the peak structural responses of the building models are studied. The effects of the GLRS modeling approach on the seismic responses are not significant in the context of seismic performance‐based design and assessment of buildings with force‐limiting connections. The effects of the SFRS modeling approach and the uncertainty in the steel model parameters on the floor total acceleration and force responses are reduced by including force‐limiting connections.
        Cover page: Reinforced concrete wall buildings with force‐limiting connections: Modeling effects and uncertainty propagationCreative Commons 'BY-NC-ND' version 4.0 license
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2023)
          Cover page: Structural connection with predetermined discrete variable friction forcesCreative Commons 'BY' version 4.0 license
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2017)
          This paper presents experimental and numerical studies of a full-scale deformable connection used to connect the floor system of the flexible gravity load resisting system to the stiff lateral force resisting system (LFRS) of an earthquake-resistant building. The purpose of the deformable connection is to limit the earthquake-induced horizontal inertia force transferred from the floor system to the LFRS and, thereby, to reduce the horizontal floor accelerations and the forces in the LFRS. The deformable connection that was studied consists of a buckling-restrained brace (BRB) and steel-reinforced laminated low-damping rubber bearings (RB). The test results show that the force–deformation responses of the connection are stable, and the dynamic force responses are larger than the quasi-static force responses. The BRB+RB force–deformation response depends mainly on the BRB response. A detailed discussion of the BRB experimental force–deformation response is presented. The experimental results show that the maximum plastic deformation range controls the isotropic hardening of the BRB. The hardened BRB force–deformation responses are used to calculate the overstrength adjustment factors. Details and limitations of a validated, accurate model for the connection force–deformation response are presented. Numerical simulation results for a 12-story reinforced concrete wall building with deformable connections show the effects of including the RB in the deformable connection and the effect of modeling the BRB isotropic hardening on the building seismic response. Copyright © 2016 John Wiley & Sons, Ltd.
            Cover page: Experimental study of deformable connection consisting of buckling‐restrained brace and rubber bearings to connect floor system to lateral force resisting system
            • Article
            • Peer Reviewed
            UC San Diego Previously Published Works (2018)
            This paper presents experimental and numerical studies of a full-scale deformable connection used to connect the floor system of the flexible gravity load resisting system to the stiff lateral force resisting system (LFRS) of an earthquake-resistant building. The purpose of the deformable connection is to limit the earthquake-induced horizontal inertia force transferred from the floor system to the LFRS and thereby to reduce the horizontal floor accelerations and the forces in the LFRS. The deformable connection that was studied consists of a friction device (FD) and carbon fiber-reinforced laminated low-damping rubber bearings (RB), denoted as the FD + RB connection. The test results show that the force-deformation responses of the FD + RB connection are stable under quasi-static sinusoidal and earthquake loading histories and dynamic sinusoidal loading histories. The FD + RB connection force-deformation response is approximated with a bilinear elastic-plastic force-deformation response with kinematic hardening. The FD is axially stiff, compact, easy-to-assemble, and able to accommodate the FD + RB connection kinematic requirements. The FD elastic stiffness controls the FD + RB connection elastic stiffness. The FD friction force controls the force when the FD + RB connection force-deformation response transitions from elastic to post elastic. The RB provide predictable and reliable post-elastic stiffness to the FD + RB connection. The machining tolerances for the FD components, the “break-in” effect, the sliding history, and the dwell time affect the FD friction force. Numerical simulation results for a 12-story reinforced concrete wall building with FD + RB connections under seismic loading show that a reduction of the FD friction force increases the FD + RB connection deformation demand.
              Cover page: Experimental study of deformable connection consisting of friction device and rubber bearings to connect floor system to lateral force resisting system
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (2016)
              This paper presents the development of a deformable connection that is used to connect each floor system of the flexible gravity load resisting system (GLRS) with the stiff lateral force resisting system (LFRS) of an earthquake-resistant building. It is shown that the deformable connection acts as a seismic response modification device, which limits the lateral forces transferred from each floor to the LFRS and allows relative motion between the GLRS and LFRS. In addition, the floor accelerations and the LFRS story shears related to the higher-mode responses are reduced. The dispersion of peak responses is also significantly reduced. Numerical simulations of the earthquake response of a 12-story reinforced concrete shear wall example building with deformable connections are used to define an approximate feasible design space for the deformable connection. The responses of the example building model with deformable connections and the example building model with rigid-elastic connections are compared. Two configurations of the deformable connection are studied. In one configuration, a buckling restrained brace is used as the limited-strength load-carrying hysteretic component of the deformable connection, and in the other configuration, a friction device is used. Low damping laminated rubber bearings are used in both configurations to ensure the out-of-plane stability of the LFRS and to provide post-elastic stiffness to the deformable connection. Important experimental results from full-scale tests of the deformable connections are presented and used to calibrate numerical models of the connections. Copyright © 2016 John Wiley & Sons, Ltd.
                Cover page: Development of deformable connection for earthquake‐resistant buildings to reduce floor accelerations and force responses
                • Article
                • Peer Reviewed
                UC San Diego Previously Published Works (2018)
                A new floor connecting system developed for low-damage seismic-resistant building structures is described herein. The system, termed Inertial Force-Limiting Floor Anchorage System (IFAS), is intended to limit the lateral forces in buildings during an earthquake. This objective is accomplished by providing limited-strength deformable connections between the floor system and the primary elements of the lateral force-resisting system. The connections transform the seismic demands from inertial forces into relative displacements between the floors and lateral force-resisting system. This paper presents the IFAS performance in a shake-table testing program that provides a direct comparison with an equivalent conventional rigidly anchored-floor structure. The test structure is a half-scale, 4-story reinforced concrete flat-plate shear wall structure. Precast hybrid rocking walls and special precast columns were used for test repeatability in a 22-input strong ground-motion sequence. The structure was purposely designed with an eccentric wall layout to examine the performance of the system in coupled translational-torsional response. The test results indicated a seismic demand reduction in the lateral force-resisting system of the IFAS structure relative to the conventional structure, including reduced shear wall base rotation, shear wall and column inter-story drift, and, in some cases, floor accelerations. These results indicate the potential for the IFAS to minimize damage to the primary structural and non-structural components during earthquakes.
                  Cover page: Shake‐table test performance of an inertial force‐limiting floor anchorage system
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