THIS RESEARCH STUDIES THE BEHAVIOR OF THE OPTIMAL PARAMETERS AND THE EFFICIENCY OF THE TUNED COMBINED DAMPER (TCD) IN THE CONTROL OF A STRUCTURE SUBJECTED TO SEISMIC EXCITATION, WHEN UNCERTAINTY IS INCORPORATED IN THE MASS RATIO AND THE LENGTH RATIO. THE TCD IS A DEVICE MADE UP OF A TUNED LIQUID COLUMN DAMPER (TLCD), AND A TUNED MASS DAMPER (TMD). SEISMIC EXCITATION IS MODELED AS A STATIONARY TYPE ZERO-MEAN GAUSSIAN STOCHASTIC PROCESS. IT IS CONSIDERED A SEISMIC EXCITATION WITH A HIGH FREQUENCY CONTENT. THE EQUIVALENT STATISTICAL LINEARIZATION METHOD IS USED TO LINEARIZE THE NONLINEAR EQUATION ASSOCIATED WITH THE TUNED FLUID DAMPER. THE SENSITIVITY OF THE OPTIMAL PARAMETERS, THE TUNING RATIO AND THE HEAD LOSS COEFFICIENT OF THE TLCD, AND THE TUNING AND DAMPING RATIO OF THE AMS ARE ANALYZED BY INCLUDING AN UNCERTAINTY IN THE MASS RATIO AND THE LENGTH RATIO. REDUCTION OF DISPLACEMENT OF THE MAIN STRUCTURE IS USED AS OPTIMIZATION CRITERION. THE TCD EFFICIENCY AND ROOT MEAN SQUARE RMS OF THE MAIN SYSTEM DISPLACEMENT ARE OBTAINED. THE RESULTS SHOW THAT THE MOST SENSITIVE PARAMETER IS THE HEAD LOSS COEFFICIENT, WHEN FACED WITH AN UNCERTAINTY IN THE LENGTH RATIO. IT IS CONCLUDED THAT THE EFFICIENCY OF THE TCD AND RMS OF DISPLACEMENT OF THE MAIN STRUCTURE IS INSENSITIVE TO AN UNCERTAINTY OF LESS THAN 10%, BOTH OF THE MASS RATIO AND THE LENGTH RATIO.

THE BEHAVIOR OF THE TUNED LIQUID COLUMN DAMPER (TLCD) IS ANALYZED IN THE CONTROL OF NON-LINEAR STRUCTURES SUBJECTED TO RANDOM SEISMIC EXCITATIONS. THE STRUCTURE IS MODELED AS A SYSTEM OF ONE DEGREE OF FREEDOM WITH INCURSION IN THE NON-LINEAR RANGE. THE BOUC-WEN HYSTERETIC MODEL IS USED TO MODEL THE NON-LINEAR BEHAVIOR OF THE STRUCTURE. A STATIONARY STOCHASTIC ANALYSIS IS PERFORMED IN THE DOMAIN OF THE FREQUENCY. AN EQUIVALENT STATISTICAL LINEARIZATION WAS USED FOR THE ANALYSIS OF THE MAIN SYSTEM AND THE TLCD. THE TLCD PARAMETERS CONSIDERED FOR THE OPTIMIZATION PROCESS WERE THE FREQUENCY AND THE HEAD LOSS COEFFICIENT. TWO TARGET FUNCTIONS WERE CONSIDERED, (I) REDUCTION OF THE MAIN DISPLACEMENT OF THE SYSTEM, (II) REDUCTION OF THE HYSTERETIC ENERGY. TWO RANDOM PROCESSES WERE CONSIDERED AS SEISMIC EXCITATION, FIRST A BROAD BANDWIDTH PROCESS AND SECONDLY A NARROW BANDWIDTH PROCESS. THE RESULTS SHOW THAT FOR A BROAD BANDWIDTH PROCESS, THE TLCD TENDS TO TUNE WITH THE LINEAR EQUIVALENT FREQUENCY OF THE SYSTEM IN THE CASE WITHOUT TLCD, WHILE FOR THE NARROW BANDWIDTH PROCESS, IT TUNES (TLCD) WITH THE DOMINANT FREQUENCY OF THE INPUT. IT IS SEEN THAT THE TLCD BECOMES DETUNED WITH REGARD TO THE FREQUENCY OF THE STRUCTURE AS THE STRUCTURE BECOMES MORE NON-LINEAR. IT IS ALSO SEEN THAT THE OPTIMAL TUNING RATIO OF THE TLCD IS UNSENSITIVE TO THE MASS RATIO OF THE DEVICE AND THE MAIN DAMPING RATIO OF THE SYSTEM. IT IS ALSO CONCLUDED THAT IN CASE OF FLEXIBLE STRUCTURES, THE OPTIMAL HEAD LOSS COEFFICIENT TENDS TO BE LOWER AND INCREASES WITH REGARD TO ITS LENGTH RATIO. IT IS SEEN THAT THE EFFECTIVENESS OF THE TLCD IS GREATER FOR HIGHER MASS RATIOS OF THE DEVICE. IN ADDITION, IT IS FOUND THAT THE OPTIMAL TLCD BECOMES LESS EFFECTIVE AS THE STRUCTURE ENTERS THE NON-LINEAR RANGE, SHOWING LOWER EFFICIENCY THAN WHAT IS SEEN IN THE LITERATURE FOR OPTIMAL TLCDS IN LINEAR STRUCTURES.

EN ESTA INVESTIGACIÓN SE ESTUDIA EL COMPORTAMIENTO DE UNA ESTRUCTURA DE UN GRADO DE LIBERTAD SOMETIDA A UNA EXCITACIÓN SÍSMICA ESTOCÁSTICA DE ALTO CONTENIDO DE FRECUENCIAS, LA CUAL ES CONTROLADA POR UN AMORTIGUADOR DE COLUMNA DE LÍQUIDO SINTONIZADO (ACLS) ÓPTIMO, CUANDO SE INTRODUCE INCERTIDUMBRE EN ALGUNOS PARÁMETROS DEL SISTEMA. SE ANALIZA LA INFLUENCIA EN EL COMPORTAMIENTO DE LOS PARÁMETROS ÓPTIMOS DEL ACLS, EN LA EFICIENCIA MEDIDA COMO REDUCCIÓN DEL DESPLAZAMIENTO DEL SISTEMA PRINCIPAL Y EN LA RAÍZ CUADRÁTICA MEDIA (RMS) DE DESPLAZAMIENTO DE LA ESTRUCTURA. SE REALIZA UNA LINEALIZACIÓN ESTADÍSTICA EQUIVALENTE PARA INCLUIR LA NATURALEZA NO LINEAL DEL ACLS. LOS PARÁMETROS ÓPTIMOS DE ACLS SON LA RAZÓN DE FRECUENCIAS Y EL COEFICIENTE DE PÉRDIDA DE CARGA. LA OPTIMIZACIÓN DEL ACLS SE REALIZA MINIMIZANDO LA REDUCCIÓN DE LA DESVIACIÓN ESTÁNDAR DEL DESPLAZAMIENTO DE LA ESTRUCTURA PRINCIPAL. LA INCERTIDUMBRE ES INGRESADA EN LA RAZÓN DE MASA, LA RAZÓN DE LONGITUD Y EL COEFICIENTE DE PÉRDIDA DE CARGA. SE ANALIZA EL COMPORTAMIENTO DE LA EFICIENCIA, MEDIDA COMO UNA REDUCCIÓN PORCENTUAL DEL DESPLAZAMIENTO AL INCLUIR UN ACLS ÓPTIMO Y EL RMS DEL DESPLAZAMIENTO, ANTE LA INCLUSIÓN DE INCERTIDUMBRE EN LOS PARÁMETROS ANTES MENCIONADOS. SE ENCUENTRA QUE LA INTRODUCCIÓN DE INCERTIDUMBRE EN EL PERIODO DE LA ESTRUCTURA PRODUCE LA MAYOR SENSIBILIDAD EN LOS PARÁMETROS ÓPTIMOS DEL ACLS, LA EFICIENCIA Y EL RMS DEL DESPLAZAMIENTO DE LA ESTRUCTURA. ESTO SE PRODUCE PRINCIPALMENTE EN ESTRUCTURAS RÍGIDAS Y CON UNA RAZÓN DE MASA PEQUEÑA. POR OTRA PARTE, UNA INCERTIDUMBRE EN LA RAZÓN DE MASA, Y EN LA RAZÓN DE LONGITUD DEL ACLS, NO PRODUCE VARIACIONES EN LA EFICIENCIA NI EN EL RMS DE DESPLAZAMIENTO DE LA ESTRUCTURA.

THE CURRENT STUDY ADDRESSES THE INFLUENCE OF THE EXCITATION FREQUENCY CONTENT ON THE EFFICIENCY OF A TUNED LIQUID COLUMN DAMPER (TLCD) TO CONTROL THE DISPLACEMENT RESPONSE IN STRUCTURES SUBJECTED TO SEISMIC EXCITATIONS. A TIME-DOMAIN STOCHASTIC STATIONARY ANALYSIS IS PERFORMED, AND AN EQUIVALENT STATISTICAL LINEARIZATION FOR THE TLCD IS OBTAINED. THE RESULTS SHOW THAT THE TLCD IS MORE EFFICIENT IN STRUCTURES SUBJECTED TO BROADBAND PROCESSES. IN NARROWBAND PROCESSES, THE MAXIMUM PERFORMANCE OF THE TLCD OCCURS WHEN THE LINEAR EQUIVALENT PERIOD OF THE SYSTEM TLCD-STRUCTURE TUNES THE TLCD PERIOD, AND THE FREQUENCY OF THE STRUCTURE MATCHES THE PREDOMINANT FREQUENCY OF THE INPUT MOTION. RESULTS DERIVED FROM THIS ANALYSIS ARE VALIDATED THROUGH TWO TIME-HISTORY SEISMIC ANALYSES.

THE INFLUENCE OF THE FRECUENCY CONTENT OF SEISMIC EXCITATIONS ON THE BEHAVIOR OF AN OPTIMAL TUNED MASS DAMPER (TMD) IS STUDIED IN THE CONTEXT OF A SYSTEM WITH EXPLICIT CONSIDERATION OF SOIL-STRUCTURE INTERACTION. A STOCHASTIC ANALYSIS IS MADE IN THE TIME DOMAIN FOR TWO RANDOM PROCESSES, ONE CONSIDERING A BROAD BANDWIDTH PROCESS (BBP) AND OTHER CONSIDERING A NARROW BANDWIDTH PROCESS (NBP). A STRUCTURE BUILT OVER THREE DIFFERENT TYPES OF SOIL (SOFT, MEDIUM AND HARD) IS CONSIDERED. FOR THE OPTIMIZATION OF THE TMD, THE MINIMIZATION OF THE RATIO BETWEEN THE STANDARD DEVIATION OF THE DISPLACEMENT OF THE MAIN STRUCTURE WITH TMD WITH RESPECT TO A STRUCTURE WITHOUT TMD, IS USED AS THE TARGET FUNCTION. IT IS FOUND THAT FOR SEISMIC EXCITATIONS WITH HIGH FRECUENCY CONTENT, THE RATIO OF THE TMD FREQUENCIES COMPARED TO THE FIXED BASE FREQUENCY OF THE STRUCTURE APPROACHES TO 1 AS THE SOIL BECOMES MORE RIGID. IT IS ALSO OBSERVED THAT THE TMD BECOME TUNED WITH THE FLEXIBLE BASE FREQUENCY FOR ALL SOIL TYPES, PRODUCING PERFECT TUNING FOR SMALL MASS RATIOS AND DETUNING GRADUALLY FOR HIGHER MASS RATIOS. ON THE OTHER HAND, THE TMD OPTIMAL DAMPING RATIO INCREASES AS THE TMD MASS RATIO IS HIGHER, INDEPENDENTLY OF THE SOIL TYPE. THE TMD IS MORE EFFICIENT FOR HIGHER VALUES OF THE TMD MASS RATIOS, ESPECIALLY ON SOFT SOIL.

EN ESTA INVESTIGACIÓN SE ANALIZA EL COMPORTAMIENTO DE UNA ESTRUCTURA LINEAL DE UN GRADO DE LIBERTAD, QUE ES CONTROLADA POR UN AMORTIGUADOR COMBINADO SINTONIZADO (ACS). ÉSTE SE COMPONE DE DOS DISPOSITIVOS, UN AMORTIGUADOR DE MASA SINTONIZADO (AMS) Y UN AMORTIGUADOR DE COLUMNA DE LÍQUIDO SINTONIZADO (ACLS). EL ACS ES SOMETIDO A UNA EXCITACIÓN SÍSMICA ESTOCÁSTICA CON EL OBJETIVO DE ANALIZAR LA INFLUENCIA DEL CONTENIDO DE FRECUENCIAS EN LA EFICIENCIA DEL DISPOSITIVO. COMO MEDIDA DE EFICIENCIA, SE CONSIDERA EL PORCENTAJE DE REDUCCIÓN DE LA DESVIACIÓN ESTÁNDAR DE DESPLAZAMIENTO DEL SISTEMA PRINCIPAL. LOS PARÁMETROS OPTIMIZADOS DE CADA DISPOSITIVO SON LA FRECUENCIA Y AMORTIGUAMIENTO EN EL CASO DEL AMS, ADEMÁS DE FRECUENCIA Y COEFICIENTE DE PÉRDIDA DE CARGA PARA EL ACLS. SE REALIZA UN ANÁLISIS DE SENSIBILIDAD DE LOS PARÁMETROS ÓPTIMOS DEL ACS, CON RESPECTO A LA RAZÓN DE MASA, PERIODO DE LA ESTRUCTURA PRINCIPAL Y CONTENIDO DE FRECUENCIAS DE LA EXCITACIÓN. LAS PRINCIPALES CONCLUSIONES OBTENIDAS, SON QUE LA EFICIENCIA DEL ACS DEPENDE DEL CONTENIDO DE FRECUENCIAS DE LA EXCITACIÓN. ADEMÁS, ESTA AUMENTA A MEDIDA QUE LA RAZÓN DE MASA AUMENTA, INDEPENDIENTE DEL CONTENIDO DE FRECUENCIAS DE LA EXCITACIÓN. POR OTRA PARTE, EL ACS ES MENOS EFICIENTE PARA ESTRUCTURAS MÁS FLEXIBLES.

IN THIS PAPER, THE BEHAVIOR OF A TUNED MASS DAMPER (TMD), TO TORSIONALLY CONTROL A LINEAR STRUCTURE SUBJECTED TO SEISMIC EXCITATIONS, IS INVESTIGATED. THE DYNAMIC SYSTEM IS ANALYZED TAKING INTO ACCOUNT LATERAL-TORSIONAL COUPLING, SOIL?STRUCTURE INTERACTION, AND THE ROTATIONAL COMPONENTS OF THE FOUNDATION MOTION. THE SYSTEM MODEL CONSISTS OF AN ASYMMETRICAL STRUCTURE, FOUNDED ON A SOIL MODELED AS A HOMOGENEOUS SEMI-SPACE. A STATIONARY STOCHASTIC ANALYSIS IS PERFORMED IN THE TIME DOMAIN, AND A DOUBLE CLOUGH-PENZIEN FILTER OF BROAD FREQUENCY CONTENT IS USED TO DEFINE THE RANDOM PROCESS FOR THE X AND Y DIRECTIONS. THE TORSIONAL BALANCE CRITERION IS EMPLOYED FOR THE OPTIMIZATION OF THE TMD DESIGN PARAMETERS. THE INFLUENCE OF THE PLAN STATIC ECCENTRICITY OVER OPTIMUM TMD PARAMETERS BEHAVIOR IS ALSO ADDRESSED, TAKING INTO ACCOUNT THE FIXED BASE PERIOD, FLEXIBLE PERIOD, TORSIONAL FREQUENCY RATIO, AND SOIL TYPE. COMPLIANCE WITH THE TORSIONAL BALANCE IS VERIFIED. THE RESULTS SHOW THAT THE INCLUSION OF THE SOIL ROTATIONAL COMPONENT HAS A NOTORIOUS INFLUENCE ON THE OPTIMUM TMD PARAMETERS. MOREOVER, TORSIONALLY FLEXIBLE STRUCTURES FOUNDED ON SOFT AND MEDIUM SOIL SHOW SIGNIFICANT INFLUENCE ON THE TORSIONAL BALANCE. FINALLY, A TRANSITORY RESPONSE ANALYSIS IS CARRIED OUT FOR A 15-STORY MODEL, SUBJECTED TO AN ARTIFICIAL BIDIRECTIONAL EARTHQUAKE WITH A BROADBAND FREQUENCY CONTENT. THE MULTISTORY MODEL RESPONSE VALIDATES THE RESULTS DERIVED FROM THE STOCHASTIC ANALYSIS.

THE EFFICIENCY OF THE TUNED MASS DAMPER (TMD) TO TORSIONALLY BALANCE NONLINEAR ASYMMETRIC STRUCTURES SUBJECTED TO UNIDIRECTIONAL SEISMIC MOTION IS STUDIED. TWO MODELS ARE ANALYZED. THE FIRST CONSISTS OF A ONE-STORY BUILDING WITH FOUR NONLINEAR RESISTANT PLANES (ORIENTED IN THE DIRECTION OF THE SEISMIC MOTION) AND TWO ELASTIC PLANES (PERPENDICULAR TO THE DIRECTION OF THE SEISMIC MOTION) WITH A LINEAR TMD. THE NONLINEAR CONSTITUTIVE RELATION OF EACH RESISTANT PLANE IS REPRESENTED BY A BOUC?WEN MODEL, AND THE SEISMIC MOTION IS MODELED AS A STATIONARY STOCHASTIC PROCESS. THE STOCHASTIC ANALYSIS OF A ONE STORY MONO-SYMMETRIC MODEL IS PERFORMED USING THE LINEAR EQUIVALENT STATISTIC TECHNIQUE. TO VALIDATE THESE RESULTS, DETERMINISTIC TIME-HISTORY ANALYSES ARE PERFORMED IN A MULTISTORY MODEL SUBJECTED TO HIGH BROAD AND NARROW BANDWIDTH SEISMIC DEMANDS. THE RESULTS SHOW THAT IN THE CASE OF TORSIONALLY FLEXIBLE STRUCTURES SUBJECTED TO A BROAD BANDWIDTH SEISMIC MOTIONS, THE TMD TENDS TO TUNE WITH THE EQUIVALENT LINEAR FREQUENCY OF THE STRUCTURE WITHOUT TMD, WHERE THE DEFORMATION OF THE MAXIMUM RESPONSE EDGE DOMINATES AND IS OPTIMALLY LOCATED IN IT. BESIDES, FOR A NARROW BANDWIDTH SEISMIC MOTIONS, THE TMDS OPTIMAL FREQUENCY IS TUNED WITH THE DOMINANT FREQUENCY OF THE SEISMIC MOTIONS. FOR BROAD BANDWIDTH SEISMIC MOTIONS, THE TMDS OPTIMAL FREQUENCY DECREASES AS THE INELASTIC INCURSION INCREASE, WHEREAS FOR THE NARROW BANDWIDTH SEISMIC MOTIONS, THE LEVEL OF NONLINEARITY DOES NOT AFFECT OPTIMAL FREQUENCY. THE TORSIONAL BALANCE CONDITION, IN GENERAL, DOES NOT LEAD TO AN EVEN DISTRIBUTION OF THE DAMAGE, BEING MORE EFFECTIVE IN STRUCTURES WITH LOW NONLINEAR DEMAND.

EN ESTA INVESTIGACIÓN SE ANALIZA EL VALOR DE LA EFICIENCIA DEL AMORTIGUADOR DE COLUMNA DE LÍQUIDO SINTONIZADO (ACLS), CALCULADA A TRAVÉS DE LA TEORÍA ESTOCÁSTICA DE VIBRACIONES. SE EMPLEAN TRES CRITERIOS O FUNCIONALES DE OPTIMIZACIÓN. EL MODELO CONSISTE EN UN SISTEMA PRINCIPAL DE UN GRADO DE LIBERTAD, CON COMPORTAMIENTO NO LINEAL, CONTROLADO POR UN ACLS NO LINEAL. EL ANÁLISIS ESTOCÁSTICO SUPONE UN ESTADO ESTACIONARIO Y REALIZA UNA LINEALIZACIÓN ESTADÍSTICA EQUIVALENTE, PARA EL COMPORTAMIENTO NO LINEAL, CON LO QUE SE OBTIENEN REDUCCIONES TEÓRICAS DE DESPLAZAMIENTO Y DE ENERGÍA HISTERÉTICA. LUEGO, ÉSTAS SE COMPARAN CON LAS REDUCCIONES OBTENIDAS CON UNA SIMULACIÓN DE MONTECARLO CON 200, 450, 800, 1250, 1850, 2600 SIMULACIONES. PARA LA SIMULACIÓN SE PLANTEAN LAS ECUACIONES NO LINEALES, QUE SE INTEGRAN DIRECTAMENTE SIN LINEALIZARLAS. LAS SIMULACIONES SE REALIZAN CON SISMOS ARTIFICIALES DE ALTO CONTENIDO DE FRECUENCIAS, COMPATIBLES CON LA NORMA CHILENA NCH2745 (2013). LOS RESULTADOS DE LA SIMULACIÓN DE MONTECARLO SON SENSIBLES AL NÚMERO DE SIMULACIONES CONSIDERADAS. SE PRODUCE UNA CONVERGENCIA PARA DOS CRITERIOS. LOS ERRORES SON MENORES AL 10%, LO QUE SE CONSIDERA ACEPTABLE. LAS REDUCCIONES OBTENIDAS PARA LA ENERGÍA HISTERÉTICA DE UN ANÁLISIS TEÓRICO, SOBRESTIMAN LA EFICIENCIA DEL ACLS, PARA UN CRITERIO CON UN PERIODO DE 2.0 S, Y PARA TODOS LOS CRITERIOS CUANDO SE TIENE UN PERIODO DE 2.5 S.