EXTERNAL AND INTERNAL EFFECTS OF FORCES ON ENGINEERED STRUCTURES PREPARED BY: ENGR. ARNOLD STEPHEN C. RADAZA ENS161 INTRODUCTION • FORCE IS DEFINED AS ANY INFLUENCE THAT CAN CHANGE THE POSITION, SPEED, AND STATE OF AN OBJECT. FORCE CAN ALSO BE DEFINED AS A PUSH OR PULL THAT ACTS ON AN OBJECT. THE FORCE ACTING CAN STOP A MOVING OBJECT, MOVE AN OBJECT FROM REST, OR CHANGE THE DIRECTION OF ITS MOTION. • FORCE IS USED IN ENGINEERING TO DESIGN AND ANALYZE STRUCTURES, MACHINES, AND OTHER SYSTEMS. IT HELPS DETERMINE THE STRENGTH, STABILITY, AND FUNCTIONALITY OF SUCH SYSTEMS, ENSURING THEY CAN WITHSTAND EXTERNAL FORCES LIKE GRAVITY, WIND, WEIGHT, AND OPERATIONAL STRESS WITHOUT BREAKING OR DEFORMING. TYPES OF FORCES • EXTERNAL FORCE A FORCE APPLIED ON AN OBJECT BY ANOTHER OBJECT NOT PART OF THE SYSTEM EXAMPLES: GRAVITATIONAL FORCE, NORMAL FORCE, AIR RESISTANCE, TENSION, AND FRICTION • INTERNAL FORCE THE FORCES THAT COMBAT THE EXTERNAL PRESSURES PLACED ON COLUMNS, BARS, AND OTHER STRUCTURE MEMBERS EXAMPLES: TENSILE AND COMPRESSIVE FORCES, SHEAR FORCES, AND BENDING MOMENTS EXTERNAL FORCES IN DETAIL I. NATURAL FORCES 1. WIND: EFFECTS ON HIGH-RISE BUILDINGS AND BRIDGES DYNAMIC AMPLIFICATION FACTOR RESONANCE - RELATIVELY LARGE SELECTIVE RESPONSE OF AN OBJECT OR A SYSTEM THAT VIBRATES IN STEP OR PHASE, WITH AN EXTERNALLY APPLIED OSCILLATORY FORCE VORTEX SHEDDING - A PHENOMENON, WHEN THE WIND BLOWS ACROSS A STRUCTURAL MEMBER, VORTICES ARE SHED ALTERNATELY FROM ONE SIDE TO THE OTHER, AND WHERE ALTERNATING LOW-PRESSURE ZONES ARE GENERATED ON THE DOWNWIND SIDE OF THE STRUCTURE GIVING RISE TO A FLUCTUATING FORCE ACTING AT RIGHT ANGLES TO THE WIND DIRECTION 2. EARTHQUAKES: SEISMIC FORCES AND STRUCTURAL RESILIENCE EARTHQUAKE RESILIENCE REFERS TO THE ABILITY OF A BUILDING TO WITHSTAND A SEISMIC EVENT WITHOUT SUSTAINING SIGNIFICANT DAMAGE OR COLLAPSE. TO BUILD AN EARTHQUAKE-RESILIENT BUILDING, WE MUST CONSIDER THE FOLLOWING: A. FOUNDATION DESIGN B. STRUCTURAL SYSTEM C. LOCATION-SPECIFIC SEISMIC ACTIVITY 3. SNOW AND RAIN: LOAD ACCUMULATION AND WATER INGRESS RAIN LOADS CAN AFFECT THE STRUCTURAL CAPACITY OF ROOFS, WALLS, AND OTHER COMPONENTS BY CAUSING LOCALIZED POOLING OF WATER AND INCREASED OVERALL WEIGHT II. MAN-MADE FORCES 1. TRAFFIC LOADS ON BRIDGES AND ROADS 2. VIBRATIONS FROM MACHINERY AND CONSTRUCTION ACTIVITIES GROUND VIBRATIONS THAT CAN CAUSE DAMAGE TO NEARBY STRUCTURES, EITHER DIRECTLY FROM WAVE PROPAGATION OR INDIRECTLY THROUGH SOIL DENSIFICATION INTERNAL FORCES IN DETAIL • TENSION THE FORCE TRANSMITTED THROUGH A ROPE, STRING OR WIRE WHEN PULLED BY FORCES ACTING FROM OPPOSITE SIDES. • COMPRESSION WHEN A PHYSICAL FORCE PRESSES INWARD ON AN OBJECT, CAUSING IT TO BECOME COMPACTED • SHEAR ARE UNALIGNED BUT PARALLEL FORCES ACTING ON A SURFACE OR ON AN OBJECT INTERACTION BETWEEN EXTERNAL AND INTERNAL FORCES • LOAD DISTRIBUTION HOW EXTERNAL FORCES TRANSLATE INTO INTERNAL STRESSES EXAMPLE: A BRIDGE UNDER A HEAVY TRUCK • STRUCTURAL RESPONSE ELASTIC AND PLASTIC DEFORMATION ELASTIC DEFORMATION – THE DEFORMATION CAUSED IS REVERSIBLE, AND THE DEFORMATION DISAPPEARS AFTER THE REMOVAL OF APPLIED FORCES. PLASTIC DEFORMATION – THE DEFORMATION IS IRREVERSIBLE AND IT STAYS EVEN AFTER THE REMOVAL OF THE APPLIED FORCES. EXAMPLE: VIBRATION AND DAMPING EFFECTS, SPRING MATERIALS AND THEIR RESPONSE TO FORCES • CONCRETE BEHAVIOR: COMPRESSION STRENGTH AND WEAKNESSES IN TENSION MANAGEMENT: REINFORCEMENT STRATEGIES (REBAR) • STEEL BEHAVIOR: HIGH TENSILE STRENGTH AND FLEXIBILITY MANAGEMENT: USE IN TENSION AND COMPRESSION APPLICATIONS • COMPOSITE MATERIALS COMBINING MATERIALS TO ENHANCE STRENGTH AND REDUCE WEAKNESSES DESIGN STRATEGIES TO MITIGATE EFFECTS • BUILDING CODES AND STANDARDS IMPORTANCE OF COMPLIANCE WITH REGULATIONS • ENGINEERING TECHNIQUES USE OF DAMPERS AND ISOLATORS IN SEISMIC DESIGN AERODYNAMIC SHAPES FOR WIND RESISTANCE • INNOVATIVE MATERIALS SMART MATERIALS AND ADAPTIVE STRUCTURES SIMULATION AND MODELING • FINITE ELEMENT ANALYSIS (FEA) OVERVIEW AND APPLICATIONS IN PREDICTING STRUCTURAL BEHAVIOR • DYNAMIC ANALYSIS SIMULATING THE EFFECTS OF DYNAMIC LOADS (E.G., EARTHQUAKES, WIND GUSTS) • CASE STUDY EXAMPLES REAL-WORLD APPLICATIONS OF SIMULATION IN DESIGN MONITORING AND MAINTENANCE • STRUCTURAL HEALTH MONITORING (SHM) 1. SENSORS AND REAL-TIME MONITORING SYSTEMS 2. IMPORTANCE OF REGULAR MAINTENANCE • FAILURE ANALYSIS 1. INVESTIGATING STRUCTURAL FAILURES AND LEARNING FROM THEM 2. PREVENTATIVE MEASURES BASED ON ANALYSIS FUTURE TRENDS IN STRUCTURAL ENGINEERING I. ADVANCEMENTS IN MATERIALS NANOTECHNOLOGY AND NEW COMPOSITES II. INNOVATIVE DESIGN APPROACHES PARAMETRIC AND GENERATIVE DESIGN III. SUSTAINABILITY ECO-FRIENDLY MATERIALS AND GREEN BUILDING PRACTICES THANK YOU!
