Control of peak floor accelerations of buildings under wind loads using tuned mass damper

Juan Acosta,Edén Bojórquez,Juan Bojórquez,Alfredo Reyes-Salazar,Omar Payán,Manuel Barraza,Juan Serrano 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.1

Due to the frequency and magnitude of some loads produced by gusts of turbulent wind, building floors can develop lateral displacements and significant accelerations which can produce strong inertial forces on structural, non-structural elements and occupants. A device that can help to reduce the floor accelerations is the well-known Tuned Mass Damper (TMD); however, nowadays there is no enough information about its capacity in order to dissipate energy of turbulent wind loads. For this reason, in this paper different buildings with and without TMD are modeled and dynamically analyzed under simulated wind loads in order to study the reduction of peak floor accelerations. The results indicate that peak floor accelerations can be reduced up to 40% when TMD are incorporated in the buildings, which demonstrated that the Tuned Mass Damper is an efficient device to reduce the wind effects on tall buildings.

Combined effect of the horizontal components of earthquakes for moment resisting steel frames

Alfredo Reyes-Salazar,José A. Juárez-Duarte,Arturo López-Barraza,Juan I. Velázquez-Dimas 국제구조공학회 2004 Steel and Composite Structures, An International J Vol.4 No.3

The commonly used seismic design procedures to evaluate the maximum effect of both horizontal components of earthquakes, namely, the Square Root of the Sum of the Squares (SRSS) and the 30- percent (30%) combination rules, are re-evaluated. The maximum seismic responses of four threedimensional moment resisting steel frames, in terms of the total base shear and the axial loads at interior, lateral and corner columns, are estimated as realistically as possible by simultaneously applying both horizontal components. Then, the abovementioned combination rules and others are evaluated. The numerical study indicates that both, the SRSS rule and the 30% combination method, may underestimate the combined effect. It is observed that the underestimation is more for the SRSS than for the 30% rule. In addition, the underestimation is more for inelastic analysis than for elastic analysis. The underestimation cannot be correlated with the height of the frames or the predominant period of the earthquakes. A basic probabilistic study is performed in order to estimate the accuracy of the 30% rule in the evaluation of the combined effect. Based on the results obtained in this study, it is concluded that the design requirements for the combined effect of the horizontal components, as outlined in some code-specified seismic design procedures, need to be modified. New combination ways are suggested.

Seismic response of 3D steel buildings with hybrid connections: PRC and FRC

Alfredo Reyes-Salazar,Jesús Alberto Cervantes-Lugo,Arturo López-Barraza,Edén Bojórquez,Juan Bojorquez 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.1

The nonlinear seismic responses of steel buildings with perimeter moment resisting frames (PMRF) and interior gravity frames (IGF) are estimated, modeling the interior connections first as perfectly pinned (PPC), and then as partially restrained (PRC). Two 3D steel building models, twenty strong motions and three levels of the PRC rigidity, which are represented by the Richard Model and the Beam Line Theory, are considered. The RUAUMOKO Computer Program is used for the required time history nonlinear dynamic analysis. The responses can be significantly reduced when interior connections are considered as PRC, confirming what observed in experimental investigations. The reduction significantly varies with the strong motion, story, model, structural deformation, response parameter, and location of the structural element. The reduction is larger for global than for local response parameters; average reductions larger than 30% are observed for shears and displacements while they are about 20% for bending moments. The reduction is much larger for medium- than for low-rise buildings indicating a considerable influence of the structural complexity. It can be concluded that, the effect of the dissipated energy at PRC should not be neglected. Even for connections with relative small stiffness, which are usually idealized as PPC, the reduction can be significant. Thus, PRC can be used at IGF of steel buildings with PMRF to get more economical construction, to reduce the seismic response and to make steel building more seismic load tolerant. Much more research is needed to consider other aspects of the problem to reach more general conclusions.

Microstructural characterization of sanitaryware by infrared and Raman spectroscopy, the role of vitreous matrix on propierties

Simón Yobanny Reyes López,Juan Serrato Rodríguez 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.1

Besides Raman and infrared spectroscopy, DSC/DTA/TGA, dilatometry, XRD, and SEM techniques were used to characterize phase transitions and microstructural evolution in porcelain stoneware. An experimental porcelain composition has been formed by slip casting and sintered in an electric furnace. Thermal evolution of raw materials shows dehydroxylation of kaolinite, transformation to spinel and mullite, and transformation of α-quartz into β-quartz evidenced by Raman spectroscopy. Spinel and granular (primary) mullite is seen to form in clay relicts which may subsequently become seeds for topotactic grown of acicular reinforcing mullite. As vitrification progresses the bridging silicon oxygen varies and can lead to connectivity changes in the silica network. The development of glassy matrix was followed by infrared spectroscopy at the porcelain intermediate sintering stage. Si-O-Si bands at 780 and 1070 cm−1 for symmetric and asymmetric stretching vibrations in the spectra have been analyzed using a polymerization index (PI). PI indicates the degree of depolymerization of the vitreous matrix through densification. PI was found to correlate well with thermal expansion, bulk density and Young’s modulus. This correlation of glass structure and properties may suggest that changes in the IR spectra could be used to predict physical properties.

Analysis of the phase transformation of aluminum formate Al(O2CH)3 to α-alumina by Raman and infrared spectroscopy

Simón Yobanny Reyes López,Rosa Saucedo Acuña,Rigoberto López-Juárez,Juan Serrato Rodríguez 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.5

A new simplified route to prepare crystalline α-alumina powders is proposed from the decomposition of aluminum formate Al(O2CH)3 precursor following a process of gelation of Al(O2CH)3 in an aqueous medium. Heat treated powders were characterized by XRD, Raman and infrared spectroscopy showing the presence of η-Al2O3 at 1000 o C and the transformation to α-Al2O3 at 1100 o C, where SEM images of α-Al2O3 reveled an size of 1-2 μm by the aggregated particles, and TEM images confirm a particles size of 200-300 nm. By other hand BET study showed that the specific surface area of η-Al2O3 and the α- Al2O3 obtained is higher than the specific surface area reported for these materials (until 118 m2 /g), ratify that this new route process at low temperature promote to obtain the powers with an excellent superficial area.

Microstructural characterization of sanitaryware, the relationship spinel and mullite

Simón Yobanny Reyes López,Juan Serrato Rodríguez,Satoshi Sugita Sueyoshi 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4

Sanitaryware reference industrial experimental compositions have been formulated, formed by slip casting and subsequently sintered in a laboratory electric furnace. Microstructural evolution was followed by HRTEM, BSE, X-ray diffraction and infrared spectroscopy. Thermal evolution of raw materials shows dehydroxylation of kaolinite, transformation to spinel and mullite, and transformation of α-quartz into β-quartz. Principal discussions are focused on the spinel and mullite evolution in the 900-1300 ο C temperature range. Evidence of the phase trans formation from spinelto mullite were found in single crystals characterized locally by fast Fourier transformand lattice fringe d spacing accounting for the coexistence of nanometric mullite with the cubic spinel phase. Back scattered electrons (BSE) in topographic mode have been used to show the presence of the spinel type intergrowth plates within the sanitaryware microstructure. Aspect ratio calculations and interplanar analysis of the distances shows less characteristic planes of spinel as mullitization and vitrification progresses, mullite planes increase up to 1250 ο C and decrease at 1300 ο C.

Response transformation factors for deterministic-based and reliability-based seismic design

Edén Bojórquez,Juan Bojórquez,Sonia E. Ruiz,Alfredo Reyes-Salazar,Juan Velázquez-Dimas 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.6

One of the main requirements of the seismic design codes must be its easy application by structural engineers. The use of practically-applicable models or simplified models as single-degree-offreedom (SDOF) systems is a good alternative to achieve this condition. In this study, deterministic and probabilistic response transformation factors are obtained to evaluate the response in terms of maximum ductility and maximum interstory drifts of multi-degree-of-freedom (MDOF) systems based on the response of equivalent SDOF systems. For this aim, five steel frames designed with the Mexican City Building Code (MCBC) as well as their corresponding equivalent SDOF systems (which represent the characteristics of the frames) are analyzed. Both structural systems are subjected to ground motions records. For the MDOF and the simplified systems, incremental dynamic analyses IDAs are developed in first place, then, structural demand hazard curves are obtained. The ratio between the IDAs curves corresponding to the MDOF systems and the curves corresponding to the simplified models are used to obtain deterministic response transformation factors. On the other hand, demand hazard curves are used to calculate probabilistic response transformation factors. It was found that both approaches give place to similar results.

Determination of the activation energy for densification of porcelain stoneware

Simón Yobanny Reyes López,Juan Serrato Rodríguez,Satoshi Sugita Sueyoshi 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.3

Experimental porcelain stoneware has been formed by slip casting and sintered by rate controlled dilatometry. Shrinkage has been measured at various constant heating rates up to 1300 oC by dilatometry. A kinetic field for stoneware firing has been set up by connecting points of equal density on the sintering rate curves to determine the activation energy for densification and to calculate optimum firing cycles. The activation energy for densification has been calculated from the slope of the isodensity curves. It has been observed that the activation energy increases with progressive sintering i.e. 470-497 kJ/mol for the intermediate sintering stage (1100-1225 oC) accounting for most of the densification. The abrupt shrinkage and low activation energy values during the intermediate sintering stage suggest a viscous flow mechanism of densification. The final sintering stage responsible for a reduced densification rate showed a lower 313 kJ/mol activation energy.

Response transformation factors for deterministic-based and reliability-based seismic design

Bojorquez, Eden,Bojorquez, Juan,Ruiz, Sonia E.,Reyes-Salazar, Alfredo,Velazquez-Dimas, Juan Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.6

One of the main requirements of the seismic design codes must be its easy application by structural engineers. The use of practically-applicable models or simplified models as single-degree-of-freedom (SDOF) systems is a good alternative to achieve this condition. In this study, deterministic and probabilistic response transformation factors are obtained to evaluate the response in terms of maximum ductility and maximum interstory drifts of multi-degree-of-freedom (MDOF) systems based on the response of equivalent SDOF systems. For this aim, five steel frames designed with the Mexican City Building Code (MCBC) as well as their corresponding equivalent SDOF systems (which represent the characteristics of the frames) are analyzed. Both structural systems are subjected to ground motions records. For the MDOF and the simplified systems, incremental dynamic analyses IDAs are developed in first place, then, structural demand hazard curves are obtained. The ratio between the IDAs curves corresponding to the MDOF systems and the curves corresponding to the simplified models are used to obtain deterministic response transformation factors. On the other hand, demand hazard curves are used to calculate probabilistic response transformation factors. It was found that both approaches give place to similar results.

Evaluation of ASCE 61-14 NSPs for the estimation of seismic demands in marginal wharves

J. Paul Smith-Pardo,Juan C. Reyes,Juan D. Sandoval,Wael M. Hassan 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.1

The Standard ASCE 61-14 proposes the Substitute Structure Method (SSM) as a Nonlinear Static Procedure (NSP) to estimate nonlinear displacement demands at the center of mass of piers or wharves under seismic actions. To account for bidirectional earthquake excitation according to the Standard, results from independent pushover analyses in each orthogonal direction should be combined using either a 100/30 directional approach or a procedure referred to as the Dynamic Magnification Factor, DMF. The main purpose of this paper is to present an evaluation of these NSPs in relation to four wharf model structures on soil conditions ranging from soft to medium dense clay. Results from nonlinear static analyses were compared against benchmark values of relevant Engineering Design Parameters, EDPs. The latter are defined as the geometric mean demands that are obtained from nonlinear dynamic analyses using a set of 30 two-component ground motion records. It was found that SSM provides close estimates of the benchmark displacement demands at the center of mass of the wharf structures. Furthermore, for the most critical pile connection at a landside corner of the wharf the 100/30 and DMF approaches produced displacement, curvature, and force demands that were reasonably comparable to corresponding benchmark values.