THE CLT MARKET IS QUICKLY GROWING AND DEVELOPING IN DIFFERENT REGIONS OF THE WORLD. HOWEVER, THE PRODUCTION AND CONSUMPTION ARE HIGHLY CONCENTRATED IN CENTRAL EUROPE (AUSTRIA, GERMANY, ITALY, AND SWITZERLAND). DUE TO THE ELEVATED LEVELS OF PERSONALIZATION REQUIRED FOR THE CONSTRUCTION PROJECTS, THE CLT MANUFACTURING PROCESS INVOLVES COSTLY AND SPECIALIZED EQUIPMENT THAT REPRESENTS AN ENTRY BARRIER FOR DOMESTIC PRODUCERS IN MARKETS WHERE THE DEMAND IS SMALL AND INCIPIENT. THIS WORK DISCUSSES A PRODUCTION MODEL AND SUPPLY CHAIN INTEGRATION FOR THE DEVELOPMENT OF THE CLT INDUSTRY IN EMERGING ENVIRONMENTS WHERE THE PRODUCT AND ITS PROPERTIES ARE NOT WELL-KNOWN. FURTHERMORE, A COMPREHENSIVE ECONOMIC ANALYSIS IS PERFORMED FOR THREE SMALL CAPACITY MILLS DESIGNED ACCORDING TO SMES CAPABILITIES. FINDINGS SUGGEST THAT CLT MANUFACTURING WITH LOW-CAPACITY PLANTS (LESS THAN 10,000 M3/YR) IS PROFITABLE BUT HIGH LEVELS OF INTEGRATION ARE REQUIRED. THE MOST INFLUENTIAL VARIABLES IN THE ECONOMIC RESULTS ARE THE LUMBER COST AND PRODUCTION VOLUME; THEREFORE, SPECIAL ATTENTION MUST BE PAID TO THE EFFICIENCY OF THE PROCESS. DESPITE THE SMALL SIZE OF THE STUDIED PLANTS PROMOTED BY THE PROPOSED PRODUCTION AND PLANT DESIGN MODEL, THE SALE PRICE IS ATTRACTIVE AND COMPETITIVE.

IN CHILE, THE CONSTRUCTION SYSTEM OF CROSS-LAMINATED TIMBER PANELS (CLT) IS EMERGING AS AN ALTERNATIVE TO ACHIEVE THE GOALS OF SUSTAINABLE CONSTRUCTION IN A COUNTRY WITH HIGH SEISMICITY. THE STIFFNESS OF THIS STRUCTURAL SYSTEM DEPENDS MAINLY ON ITS CONNECTIONS, WHICH GENERALLY CONSIST OF STEEL ELEMENTS OF SMALL THICKNESS THAT ARE NAILED OR SCREWED TO THE WOOD. WHEN SEISMIC MOVEMENTS OCCUR, THESE JOINTS LOSE STIFFNESS DUE TO THE DAMAGE CAUSED BY THE FLUENCE OF THE CONNECTORS AND CRUSHING IN THE WOOD. THESE DAMAGES ARE USUALLY HIDDEN BY THE FINISHING BOARDS OF WALLS AND SLABS, SO IT IS DIFFICULT TO INSPECT THEM AFTER A SEISMIC EVENT. THE OBJECTIVE OF THE PRESENT WORK IS TO ESTIMATE THE LOSS OF STIFFNESS OF CLT WALLS THROUGH NON-DESTRUCTIVE VIBRATION-BASED TESTS. TWO CLT WALLS OF TWO-STORY HEIGHT (SECTION H 2400MM X 4200MM X 1200MM) ARE CONSTRUCTED, WITH THEIR RESPECTIVE CONNECTORS, AND THEN SUBJECTED TO NON REVERSIBLE CYCLIC HORIZONTAL LOAD TESTS. THE WALLS ARE INSTRUMENTED WITH ACCELEROMETERS, AND MODAL IMPACT TESTS ARE APPLIED AFTER EACH HORIZONTAL LOAD CYCLE, OBTAINING THE VARIATION OF THEIR DYNAMIC PROPERTIES. THE EXPERIMENTAL RESULTS SHOW THAT WHEN THE GLOBAL TANGENT STIFFNESS OF THE WALL REACHES 28% OF THE ORIGINAL VALUE, THE FUNDAMENTAL PERIOD OF VIBRATION INCREASE BY 1.52 TIMES. IN THIS WAY, THE POTENTIAL OF THIS NON DESTRUCTIVE TECHNIQUE FOR SEISMIC INSPECTION AND REHABILITATION OF BUILDINGS WITH CLT PANELS IS OBSERVED.

CROSS-LAMINATED-TIMBER (CLT) STRUCTURES HAVE GAINED POPULARITY IN THE FIELD OF MEDIUM-RISE BUILDINGS DUE TO THE QUICK FABRICATION AND ASSEMBLY OF THE PANELS. HOWEVER, CONNECTIONS IN RADIATA PINE CLT SHEAR WALLS AND THE BEHAVIOR OF CLT STRUCTURES UNDER LATERAL LOADS IS STILL NOT WELL UNDERSTOOD. IN THIS CONTEXT, THIS PAPER STUDIES THE STRUCTURAL BEHAVIOR OF HOLD-DOWN CONNECTIONS ON RADIATA PINE CLT WALLS BY MEANS OF EXPERIMENTAL TESTS AND NUMERICAL SIMULATIONS UNDER STATIC AND DYNAMIC CONDITIONS. THE TEST RESPONSE OF CONNECTIONS WAS REPLICATED BY CALIBRATING TWO HYSTERETIC MODELS ON OPENSEES. THE MAIN RESULTS SHOWED THAT APPLIED MODELS CAN REPRODUCE THE HYSTERETIC BEHAVIOR OF HOLD-DOWN CONNECTIONS WITH HIGH PRECISION. IT WAS OBSERVED THAT HOLD-DOWN CONNECTIONS ON RADIATA PINE CLT WALLS REACHED A LOADING CAPACITY SIMILAR TO OTHER WOOD SPECIES, BUT THE STRENGTH AND STIFFNESS DEGRADATION WAS QUICKER, AND NO SIGNIFICANT DIFFERENCE WITH THE PARALLEL TO GRAIN CAPACITY OF ANGLE BRACKET CONNECTIONS WAS NOTICED. IN ADDITION, IT WAS FOUND THAT RADIATA PINE CLT WALLS CAN ACHIEVE SUITABLE CYCLIC LOADING PERFORMANCE WITH LOW DAMAGE LEVEL IN CONNECTIONS AND REACH HIGH LEVELS OF DISPLACEMENT DUCTILITY. FINALLY, THE IMPORTANCE OF FRICTION IN THE LOAD CAPACITY OF THE WALL WAS ALSO SHOWN.

THIS STUDY EXAMINES EXPERIMENTALLY AND NUMERICALLY THE IN-PLANE BEHAVIOR OF A STEEL-SPLINE CROSS-LAMINATED TIMBER (CLT) CONNECTION WITH SELF-TAPPING SCREWS. ALTHOUGH THIS CONNECTION IS A STRONG, RAPID, AND COST-EFFECTIVE ALTERNATIVE SUITABLE FOR CLT DIAPHRAGMS OF TALL TIMBER-CONCRETE BUILDINGS, NO PREVIOUS CYCLIC/MONOTONIC TESTING HAS BEEN DOCUMENTED. TWO SPECIMENS WERE TESTED UNDER AXIAL AND IN-PLANE SHEAR LOADS, WHERE A DUCTILE FAILURE MODE WAS OBSERVED DUE TO BENDING AND WITHDRAWAL OF SCREWS, AND DEFORMATION AND BUCKLING OF THE STRAP. MECHANIC PROPERTIES, SUCH AS STRENGTH CAPACITY, STIFFNESS, DUCTILITY, ENERGY DISSIPATION, EQUIVALENT VISCOUS DAMPING, STIFFNESS/STRENGTH DEGRADATION, AND DAMAGE INDEX CHARACTERIZE THE JOINT. FURTHERMORE, THE YIELD POINT AND DUCTILITY WERE CALCULATED WITH THE EEEP, CEN, AND YASUMURA-KAWAI METHODS, THE LAST APPROACH MOST ACCURATE, WITH A MEAN DUCTILITY OF 7.25 AND 5.50 FOR THE AXIAL AND IN-PLANE SHEAR TESTS, RESPECTIVELY. OVERSTRENGTH FACTORS OF ABOUT 2.6 AND 1.9 WERE ALSO ESTIMATED FOR RESPECTIVE TESTS BY COMPARING ANALYTICAL EXPRESSIONS FROM TIMBER CODES AND LITERATURE. FINALLY, THREE NUMERICAL MODELS (SAWS, DOWELTYPE, AND ASPID) WERE ASSESSED TO MEASURE THEIR EPISTEMIC UNCERTAINTY, SHOWING AN ADEQUATE FORCE AND DISSIPATED ENERGY HISTORY SIMULATION, WITH A NORMALIZED ROOT MEAN SQUARE LESS THAN 8.8% AND 4.5%, AND R(2 )OVER 87% AND 97%, RESPECTIVELY.

SINCE THE LARGE SEISMIC DEMANDS IN CHILE, THERE IS A HIGH LEVEL OF UNCERTAINTY REGARDING THE SEISMIC SAFETY BEHAVIOR OF TIMBER STRUCTURES. BESIDES, IN THE LAST DECADE, THERE HAS BEEN A WORLDWIDE RISE IN THE CONSTRUCTION OF CROSS-LAMINATED TIMBER (CLT) BUILDINGS, EXPLAINED BY THE EASE OF INDUSTRIALIZATION OF CLT PANELS AND FOR BEING A SUSTAINABLE MATERIAL. HOWEVER, ITS MASSIFICATION IN HIGH EARTHQUAKE-PRONE ZONES IS STILL UNDER DEVELOPMENT. THIS RESEARCH ANALYZES THE SEISMIC FRAGILITY OF A 5-STORY CLT BUILDING. THE AIM OF THIS RESEARCH IS TO DETERMINE THE SEISMIC SAFETY LEVEL OF A CLT MIDRISE BUILDING DESIGNED BY CHILEAN FORCE-BASED CODE REGULATIONS BY MEANS OF STATIC NONLINEAR ANALYSIS AND INCREMENTAL DYNAMIC ANALYSIS. FOR IDA CURVES, A SET OF 540 NONLINEAR TIME-HISTORY ANALYSES WERE PERFORMED USING PARALLEL COMPUTING TOOLS. THE MAIN RESULTS SHOW THAT FOR THE COLLAPSE OF THE BUILDING TO OCCUR, LARGE PSEUDO-ACCELERATION VALUES NEED TO BE REACHED. BESIDES, THE COLLAPSE MARGIN RATIO (CMR) IS CALCULATED FOR THE TWO PRINCIPAL DIRECTIONS, ACHIEVING VALUES LARGER THAN 3 FOR 50% COLLAPSE PROBABILITY. THESE RESULTS SUGGEST A LARGE MARGIN OF SEISMIC SAFETY OF THE CLT BUILDING DESIGNED IN THIS RESEARCH.

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.

THIS PAPER PRESENTS A METHODOLOGY TO EVALUATE THE DAMAGE IN CLT WALLS BY APPLYING NON-DESTRUCTIVE VIBRATION-BASED METHODS. THE MAIN CONTRIBUTION IS THAT THE METHODOLOGY ALLOWS LOCATING THE DAMAGE AND ESTIMATING THE SEVERITY OF DAMAGE IN THE DIFFERENT WALL JOINTS, GOING BEYOND THE TYPICAL GLOBAL DAMAGE DETECTIONS. ONE OF THE RELEVANT ASPECTS WAS THE NOVEL COMBINATION OF OPERATIONAL MODAL ANALYSIS, FINITE ELEMENT MODEL UPDATING, AND REGIONAL SENSITIVITY ANALYSIS. THE METHODOLOGY WAS SUCCESSFULLY APPLIED TO A 2-STORY CLT MODULE BUILT IN THE LABORATORY AND INSTRUMENTED WITH ACCELEROMETERS. THE WALL WAS EVALUATED IN 11 DIFFERENT DAMAGE SCENARIOS INDUCED BY INCREMENTAL PSEUDO-STATIC LATERAL LOADS. THE RESULTS OBTAINED CORRELATED REASONABLY WELL WITH THE VISUALLY OBSERVED DAMAGE, SO IT IS ESTIMATED THAT THIS METHODOLOGY COULD BE EXTENDED TO MORE COMPLEX CLT WALL CONFIGURATIONS.

THE USE OF CROSS-LAMINATED TIMBER PANELS (CLT) MADE OF LOW-GRADE STRUCTURAL TIMBER HAS STEADILY INCREASED IN DEVELOPING COUNTRIES. THESE PANELS USUALLY PRESENT SEVERAL NATURAL DEFECTS, WHICH CAN CAUSE A HIGH LOCAL VARIATION OF THEIR ORTHOTROPIC ELASTIC PROPERTIES, GENERATING FUTURE STRUCTURAL SERVICEABILITY PROBLEMS. OUR WORK AIMS TO ESTIMATE THE LOCAL VARIABILITY OF THE ELASTIC PROPERTIES IN LOW-GRADE CLT PANELS BY COMBINING NONDESTRUCTIVE TRANSVERSE VIBRATION TESTING, NUMERICAL SIMULATIONS, AND REGIONAL SENSITIVITY ANALYSIS (RSA). FOUR THREE-LAYER RADIATA PINE CLT PANELS WERE SUBJECTED TO TRANSVERSE VIBRATION TESTS WITH SUPPORTS AT FOUR POINTS. BESIDES, A SERIES OF NUMERICAL SIMULATIONS OF THE PANELS, CONSIDERING THE LOCAL VARIABILITY OF THE ELASTIC PROPERTIES OF THE PANELS IN EIGHT ZONES, WERE CARRIED OUT USING THE FINITE ELEMENT METHOD. THEN, RSA ANALYSIS WAS PERFORMED TO STUDY IN WHICH RANGES OF VALUES THE PANELS? ELASTIC PROPERTIES GENERATED LOWER DIFFERENCES BETWEEN THE MEASURED VERSUS SIMULATED DYNAMIC PROPERTIES. FINALLY, A STRUCTURAL QUALITY CONTROL INDICATOR WAS PROPOSED FOR THE CLT PANELS BASED ON KEEPING LOW THE PROBABILITY THAT THE ELASTIC PROPERTIES IN THE CENTRAL ZONES DO NOT EXCEED MINIMUM ACCEPTABLE VALUES. THE RESULTS OBTAINED SUGGEST THAT THE PROPOSED METHODOLOGY IS SUITABLE FOR SEGREGATING CLT PANELS WITH HIGH CONCENTRATIONS OF DEFECTS SUCH AS PITH PRESENCE.

THE SEISMIC ANALYSIS OF MASS TIMBER STRUCTURES THROUGH NUMERICAL MODELS IS CHALLENGING DUE TO THE SYSTEM'S LARGE NUMBER OF NONLINEAR COMPONENTS AND THE COMPLEX FAILURE MECHANISMS DEVELOPED. ADDITIONALLY, IF LONG-DURATION MEGATHRUST EARTHQUAKE RECORDINGS NEED TO BE CONSIDERED, THE TIME CONSUMPTION OF THE COMPUTATION INCREASE SIGNIFICANTLY. THEREFORE, REFINED AND ADVANCED NONLINEAR NUMERICAL MODELS THAT DEMAND HIGH COMPUTATION CAPACITY NEED TO BE CONSIDERED. IN ORDER TO ANALYZE THE LATERAL BEHAVIOR OF CROSS-LAMINATED-TIMBER STRUCTURES, DETAILED COUPLED THREE-DIMENSIONAL NUMERICAL MODELS WERE DEVELOPED IN OPENSEESMP. EVERY COMPONENT OF THE CLT SYSTEM WAS INCLUDED (WALLS, SLABS, SCREWS, AND MECHANICAL CONNECTIONS), AS WELL AS THE FRICTION AND CONTACT INTERACTION AT THE FOUNDATION FLOOR SLABS AND THE WALL-TO-WALL INTERFACE. THE NUMERICAL MODELS? SIZE WAS AROUND 120.000 DOF. IN THIS RESEARCH, SEQUENTIAL AND PARALLEL MODELING TECHNIQUES WERE COMPARED USING STANDARD DESKTOP PCS (8 CORES I7 PROCESSOR). FOR THE IMPLEMENTATION OF THE PARALLEL MODELS, A STATIC DECOMPOSITION APPROACH WAS USED. EIGHT AND THREE CORES WERE EMPLOYED TO PERFORM THE ANALYSES; THEREFORE, THE PARALLELIZATION CONSIDERS THE SEGMENTATION INTO THREE AND EIGHT SUBDOMAINS, RESPECTIVELY. A TOTAL OF 6-TIME HISTORY ANALYSES USING LONG-DURATION SUBDUCTION EARTHQUAKE RECORDINGS FOR EACH CASE OF STUDY WERE PERFORMED. MAIN RESULTS SHOW THAT THERE IS A 50%-TIME REDUCTION IN THE PARALLEL WITH RESPECT TO THE SEQUENTIAL MODELING APPROACH. HOWEVER, INCREASING FROM THREE TO EIGHT PROCESSING CORES MARGINALLY IMPROVES THE PERFORMANCE OF THE NUMERICAL MODELS.