Statics Dr. Aeid A. Abdulrazeg Course Code: CIVL211 Dr. Aeid A. Adulrazeg (Statics)

Contents: 1. Define the types of force system, equations of equilibrium and different supporting system in structure. 2. Apply the equations of equilibrium to determine the reaction forces of beams, frames and cables. 3. Apply the equations of equilibrium in analyzing plane trusses using method of joint and section. 4. Explain the concept of friction and its application in civil engineering. 5. Determine the geometrical properties of different section.

Assessment Details Assessment Percentage % Due Assignments 10% Week 4, 10, 14 Quizzes Week 5, 11 Mid-term exam -1 20% Week 6 Mid-term exam-2 Week 12 Final Exam 40% Week 16 or 17

WHAT IS MECHANICS? Mechanics can be defined as that science which describes and predicts the conditions of rest or motion of bodies under the action of forces. Mechanics of Engineering Mechanics of rigid bodies Mechanics of deformable bodies Mechanics of fluids Statics Dynamics Why we study mechanics? Design and analysis of structures

Mechanics of rigid bodies Statics: the study of bodies in equilibrium Dynamics: 1. Kinematics – concerned with the geometric aspects of motion 2. Kinetics - concerned with the forces causing the motion Dr. Aeid A. Adulrazeg (Statics)

WHAT MAY HAPPEN IF STATICS IS NOT APPLIED PROPERLY? Dr. Aeid A. Adulrazeg (Statics)

Basic Concepts The following concepts and definitions are basic to the study of mechanics: Space is the geometric region occupied by bodies whose positions are described by linear and angular measurements relative to a coordinate system. Time is the measure of the succession of events and is a basic quantity in dynamics. Mass is a measure of the inertia of a body, which is its resistance to a change of velocity. Force is the action of one body on another. A force tends to move a body in the direction of its action. A particle is a body of negligible dimensions. In the mathematical sense, a particle is a body whose dimensions are considered to be near zero so that we may analyze it as a mass concentrated at a point. Rigid body A body is considered rigid when the change in distance between any two of its points is negligible for the purpose at hand.

Newton’s Laws Law I. if the resultant force action on a particle is zero, the particle will remain at rest (if originally at rest) or will move with constant speed in straight line (if originally in motion). Law II. if the resultant force action on a particle is not zero, the particle will have an acceleration proportional to the magnitude of the resultant and in the direction of this resultant force. Law II. The force of action and reaction between bodies in contact have the same magnitude, same line of action, and opposite sense.

UNITS OF MEASUREMENT Four fundamental physical quantities. Length Mass Time Force Newton’s 2nd Law relates them: F = m * a We use this equation to develop systems of units. Units are arbitrary names we give to the physical quantities. Dr. Aeid A. Adulrazeg (Statics)

UNIT SYSTEMS Force, mass and acceleration are called the base units. The fourth unit, time is derived from the acceleration term. We will work with two unit systems in statics: International System (SI) U.S. Customary (USCS) Dr. Aeid A. Adulrazeg (Statics)

Dr. Aeid A. Adulrazeg (Statics)

COMMON CONVERSION FACTORS Work problems in the units given unless otherwise instructed! 1 ft = 0.3048 m 1 lb = 4.4482 N 1 slug = 14.5938 kg Example: Convert a torque value of 47 in • lb into SI units. Answer is 5.31026116 N • m? Dr. Aeid A. Adulrazeg (Statics)

THE INTERNATIONAL SYSTEM OF UNITS (Section 1.4) No Plurals (e.g., m = 5 kg not kgs ) Separate Units with a • (e.g., meter second = m • s ) Most symbols are in lowercase. Some exceptions are N, Pa, M and G. Exponential powers apply to units, e.g., cm • cm = cm2 Compound prefixes should not be used. When writing exponential notation 4.5x103 N *NOT* 4.5E3N Dr. Aeid A. Adulrazeg (Statics)

PROBLEM SOLVING STRATEGY: IPE, A 3 Step Approach 1. Interpret: Read carefully and determine what is given and what is to be found/ delivered. Ask, if not clear. If necessary, make assumptions and indicate them. 2. Plan: Think about major steps (or a road map) that you will take to solve a given problem. Think of alternative/creative solutions and choose the best one. 3. Execute: Carry out your steps. Use appropriate diagrams and equations. Estimate your answers. Avoid simple calculation mistakes. Reflect on / revise your work. Dr. Aeid A. Adulrazeg (Statics)