Dr. Núñez-Castellanos, Eduardo

The incremental dynamic analysis is procedure highly used in the evaluation of structural systems and seismic design parameters for the linear design methods traditionally used in current building codes. The use of this methodology has been extended to industrial structures; however, in the case of steel racks subjected to subduction earthquakes such as the one in Chile, the procedure presents limitations in the post MCE scaling stage due to the high seismic demand, which does not allow its use. In this research, the seismic evaluation of steel storage racks is studied using a dynamic decremental analysis (DDA). The numerical research aims at a methodology proposed to evaluate seismic damage in steel storage racks, considering operational continuity, life safety and collapse prevention levels. A total of 4840 nonlinear models were performed to establish the performance levels, supported by the principles of the IDA according to FEMA P695. The MCE is used to scale the seismic records, however, a decremental scaling process is applied to identify the performance gap between the design intensity and the MCE intensity. The results obtained showed that the archetypes with lower load levels and lower height exhibited higher performance levels in the down-aisle direction compared to the transverse direction. In addition, the proposed methodology allows obtaining a performance level considering the seismic forces scaled to the MCE level through a methodology on steel racks, which had not been possible to evaluate using the IDA. Finally, the main problem in the study of steel racks design is to ensure the stability in the cross-aisle direction and stability of the stored goods in that direction.

This article presents the validation of a load-level isolation system designed for seismic protection and vibration control of industrial storage racks. This system exhibits the necessary versatility to protect the structure against different seismic intensities. The objective is to verify the effectiveness of the studied load-level isolation system in reducing the structural response and improving the seismic performance of the industrial racking, validating it with experimental tests. This was carried out on a shaking table with a total of 12 two-level rack tested at full scale, with 6 in conventional use conditions and 6 with the load-level isolation system. The 2010 earthquake in El Maule, Chile, was used as a forcing, scaled in the frequency domain to adjust its response spectrum with the design spectrum of NCh2369Of.2023. In the tests, the amount and distribution of the mass were varied, repeating the test for the design earthquake scaled to 10 %, 20 %, … 100 %. The results indicated that the implementation of the isolation system achieved a reduction of between 40 % and 81 % in floor deformations, and between 49 % and 63 % in the base shear, being able to resist up to at least 120 of the design earthquakes considered. The isolation system proved effective in protecting the structural integrity of the storage rack from low, medium, and high-intensity earthquakes.

In this research an experimental study to assess the cyclic behavior of bolted moment connection in racks structures is performed. The effect of bolt pretension in the response is evaluated. Sixteen full-scale steel rack joint configurations were subjected to cyclic load according to the protocol established in AISC Seismic provisions. The cyclic performance was evaluated in terms of hysteretic response, failure mechanism, energy dissipation, stiffness, and rotation on the components. Two different configurations were studied. The results showed that the steel rack connections using a 70 % of bolt pretension can accommodate a 0.8 My at 0.04 rad of drift angle, while the joints without bolt pretension reached values below 0.7 My at 4 % of rotation. The failure mechanism was controlled by weld fracture at 4 % of the rotation. A high dispersion in the energy dissipation pattern was obtained and a drop in energy dissipation of up to 4 times in all specimens tested for a 4 % rotation was developed. This phenomenon is due to the welding rupture between the beam and the L-connector. A degradation of the secant stiffness reached up to 60 % for 2 % rotation. Finally, the most important effect of bolt pretension on the cyclic response of steel rack connections was achieved in the increase of flexural resistance and rotation developed.

In this research, the cyclic behavior of concrete-filled thin tube (CFTT) columns with bidirectional moment connections was numerically studied within the context of thin-walled structures. Novel considerations in the design of CFTT columns with slenderness sections are proposed through a parametric study. A total of 70 high-fidelity finite element (FE) models are developed using ANSYS software v2022 calibrated from experimental research using similar 3D joint configurations. Furthermore, a comparison of different width-to-thickness ratios in columns was considered. The results showed that the models with a high slenderness ratio reached a stable cyclic behavior until 0.03 rad of drift, and a flexural strength of 0.8 Mp was reached for 4% of the drift ratio according to the Seismic Provisions. However, this effect slightly decreased the strength and the dissipated energy of the moment connection in comparison to columns with a high ductility ratio. Moreover, an evaluation of concrete damages shows concrete cracked for cyclic loads higher than 3% of drift. Finally, the joint configurations studied can achieve a good performance, avoiding brittle failure mechanisms and ensuring the plastic hinges in the beams.

This research raises questions about the possibilities and options of using the BIM methodology associated with software for the wood design and construction of structure modeling along an asset’s cycle life. Likewise, several academic and research initiatives are reviewed. In this sense, this paper aims to establish an appropriate link between two agendas that the architecture, engineering, and construction (AEC) industry, academia, and governments normally handle separately. By conducting several literature reviews (book, journals, and congresses) and extensive software tests (BIM software: Revit v2023, Archicad v27, Tekla, and wood plug-ins: AGACAD, Archiframe, Timber Framing 2015, WoodStud Frame, etc.), the state-of-the-art was assessed in both fields, and several cases linking BIM and wood are shown in detail and discussed. Various theoretical samples are modelled and shown, and the advantages and disadvantages of each technique and stage are explained. On the other hand, although wood construction has been most common for hundreds of years, this is not the case of BIM software developments associated with this materiality. Furthermore, since the appearance of materials such as steel and reinforced concrete, all software developments have focused on these materials, leaving aside the possibility of developing applications for use in wood projects. According to that previously discussed, it can be concluded that BIM for wood has been used more frequently in academia, that both fields have several common processes, and, in many cases, that only a few BIM-wood tools have been used, thus disregarding the high potential and high level of benefits that result with the application of these methodologies for the complete building life cycle (design, construction, and operation).

This paper introduces a system allows for seismic isolation of the pallet from the rack in the down-aisle direction, occupies minimal vertical space (5 cm) and ±7.5 cm of deformation range. A conceptual model of the isolation system is presented, leading to a constitutive equation governing its behavior. A first experimental campaign studying the response of the isolation system's components was conducted to calibrate the parameters of its constitutive equation. A second experimental campaign evaluated the response of the isolation system with mass placed on it, subjected to cyclic loading. The results of this second campaign were compared with the numerical predictions using the pre-calibrated constitutive equation, allowing a double-blind validation of the constitutive equation of the isolation system. Finally, a numerical evaluation of the isolation system subjected to a synthetic earthquake of one component. This evaluation allowed verifying attributes of the proposed isolation system, such as its self-centering capacity and its effectiveness in reducing the absolute acceleration of the isolated mass and the shear load transmitted to the supporting beams of the rack.

The study of moment connections in steel structures subjected to cyclic loads has been extensively studied, providing a great number of requirements, including the strong column-weak beam relationship, to guarantee a satisfactory cyclic performance. However, investigations on the cyclic performance of moment connections considering the bidirectional and axial load effects simultaneously with tubular columns are limited. This study aims to assess and validate the strong column-weak beam relationship of 3D steel moment connections using reduced order models. The simplified model (reduced order model) approach was employed to extend the range of beam and column elements sizes and reduce the experimental and computational costs. These models were calibrated from full-scale experimental studies. A great number of configurations with different beam and column sizes without loss of reliability and structural representativeness of the studied phenomenon were studied. A total of 13640 simplified models were developed. Results show a cyclic behavior controlled by the strong column-weak beam relationship to modify the joint’s failure mechanism. The increasing of strong column-weak beam relationship and the biaxial effect caused degradation of the strength and stiffness as well as in dissipated energy. An optimal strong column-weak beam relationship was obtained for all joint configurations analyzed. Finally, a robust design procedure is proposed, ensuring the cyclic behavior of end-plate moment connection with built-up box column including biaxial effect and axial load. Therefore, the use of this type of moment connection can be used in special and intermediate moment frames designed according to Seismic provisions.

BIM models are seldom used for the energy certification of buildings. This paper discusses the advantages of linking two important fields: building information modeling (BIM) and building environmental assessment methods (BEAM), presented as a rating system and a proposal for the Chilean context. The state of the art in both fields around the world is discussed, with an in-depth examination of current BIM software and related applications, followed by a discussion about previous research on integrating them. A lack of interoperability and data losses between BIM and BEM were found. A new tool is presented that addresses these challenges to ensure accurate rating system data, and this new framework is based on database exchange and takes crucial information from BIM to BEAM platforms. The development of the method includes BIM programming (API), database links, and spreadsheets for a Chilean building energy certification through a new tool, also applicable to multiclimactic zones. This new semi-automatic tool allows architects to model their design in a BIM platform and use this information as input for the energy certification process. The potential and risks of this method are discussed. Several improvements and enhancements of the energy certification process were found when incorporating this new framework in comparison to current methodologies.

The use of column-tree connections is common in controlled shop environments due to their cost-effectiveness in achieving ductile welds. Field bolts are also easy to install and inspect. However, there is currently no prequalification available for these connections, their performance is not fully understood, and the cost of aftermath repairs is still a major concern for owners. In this research, analytical and numerical studies were performed to assess the cyclic behavior considering the effects of the bolted splice location, bolt slippage, and splice plate thickness. Fourteen numerical models using the finite element method in ANSYS software were analyzed to evaluate the nonlinear behavior of moment connection configurations in terms of the strength, stiffness, ductility, energy dissipation, and overall cyclic response. The results showed that appropriately proportioned bolted splice connections can meet the requirements for prequalified moment connections. The models complied with the criteria established in AISC 358 and achieved flexural resistance that was higher than 80% of the beam plastic moment at 4% of the interstory drift ratio. The weakened plates concentrated the inelastic action, which allowed us to prevent the brittle behavior and damage to the column, welding, and other components of the moment connection. Complex geometries or specially fabricated parts were not required, providing a cost-effective way to control seismic-related damage. Also, required repairs are based on the replacement of standard parts, reducing operational detentions in facilities. Finally, the moment connection studied is classified as partially restrained (PR) according to the requirements established in AISC 360.

Concrete strength assessment is an important topic in evaluating existing structures. Formerly, only destructive tests were employed, limiting the number of tests due to their complexity and cost. Nowadays, the application of non-destructive tests has been booming to determine material strength, offering a more accessible and cheaper strategy than its counterpart. Non-destructive strategies are based on two steps: (1) the identification of the correlation between the concrete strength and another parameter that is easy to measure in situ, and (2) the use of this easy-to-measure parameter to infer the concrete strength in any desired element of the structure. The most common parameter adopted for this purpose is the Ultrasonic Pulse Velocity (UPV). However, the correlation between concrete strength and UPV must be determined via destructive experiments. From the research perspective, attention has focused on determining the correlation coefficient and the range of credibility for estimating the inferred concrete strength. Despite it, this strategy has remained elusive in the fundamental understanding and accounting of the joint dispersion of the concrete strength and the UPV. The present work addresses this knowledge gap by proposing a new correlation method based on probability interpretations to infer the compressive concrete strength from in-situ UPV measurements and including the dispersion evidenced in UPV measurements in both steps mentioned. The results demonstrated that it is possible to determine the confidence interval for the concrete compressive strength given a certain percentile of the UPV measured in situ. Finally, the application of the proposed method is illustrated through a case study, which is representative of different building pathologies. This novel proposal is a foundation to deal with the uncertainties involved in non-destructive tests, inspiring future advances in this field.