2 CIVIL ENGINEERING PROJECT FORCES ONCIVIL ENGINEERING PROJECTLEARNING OUTCOMES :a) Identify and describe the engineering forces due to;Physical forces Dead load, traffic loads, imposed loads, hydrostatic/ water pressure, lateral earth pressureEnvironmental forces Wind, earthquake, waves, explosion, flood, temperature and pollutantsb) Identify and describe the engineering forces based on chosen case project.
3 INTRODUCTIONIn any building design, the strength and stability of an overall building and its individual components must be considered.This involves structural calculations to workout the effects of all the forces acting on any component in the building and on thebuilding overall.To do this we need to resolve the forces in the system to see what the overall effectsare likely to be.
4 INTRODUCTIONAn overview of the many different forces acting on a building.
5 INTRODUCTIONA summary of all the forces acting on the building. The dotted arrow is the resultant force, a force representing the overall effect of the loads.
6 INTRODUCTION Structural Engineering What does a Structural Engineer do?A Structural Engineer designs the structural systems and structural elements in buildings, bridges, stadiums, tunnels, and other civil engineering worksDesign:process of determining location, material, and size of structural elements to resist forces acting in a structure6
9 i) DEAD LOAD Dead loads are permanent or stationary loads which are transferred to structure throughoutthe life span.Dead load is primarily due to- self weight of structural members- permanent architectural component such as exterior cladding, partitions and ceilings- equipment and static machinery when permanent fixtures
10 A Simply Supported Beam TensionCompressionLoads10
11 ii) LIVE LOAD/IMPOSED LOAD The total of all moving and variable loads that may be placed upon a building or homeLoad that acts on structural component.Loads produced by use and occupancy of the building structure including weights of movable partitions or furniture etc.These load are more difficult to determine accurately.Estimates done on standard codes of practice or past experience.11
12 Towers: Live and Dead Loads EXAMPLETowers: Live and Dead LoadsTowers serve many purposes. Radio, TV and wireless communication signals are transmitted from towers. Forest rangers keep a vigilant eye peeled for signs of forest fires from observation towers. Skyscrapers serve an important role in the world’s urban areas.Like other structures, towers are subjected to dead and live loads. In the case of a skyscraper, dead loads are comprised of steel columns and beams, concrete, and glass – the weight of the structure itself. Live loads include the people milling about on the floors and ascending the elevators; plus furniture, materials, and goods that move into the building.Another important live load acting on a skyscraper is the force of wind blowing against the exterior surfaces. Because the buildings have an enormous amount of surface area, the force of wind on a skyscraper can be extremely powerful.
13 ii) TRAFFIC LOADTraffic load is the average number ofvehicles two-way passing a specific point in a 24-hour period, normally measured throughout a yearThe standard measurement for vehicle traffic load on a section of road, and the basis for most decisions regarding transport planning.Road authorities have norms based on traffic load with decisions to expand road capacity.13
14 COMPOSITION OF TRAFFIC STREAM Based on the various sizes of vehicles using intersectionPCU (Passenger Car Unit) is used to calculate trafficstreamVehicle TypeEquivalent Value (pcu)MotorcyclePassenger carMedium LorryLight VanBus & Heavy Lorry0.331.001.752.002.25EQUIVALENT FACTOR FOR VARIOUS VEHICLES RELATIVE TO PASSENGER CAR
15 Traffic Force Transfer Example - Bridge 8,000 lb32,000 lb22,000 lb*18,000 lb**L = 60 ft30 ft15 ft45 ft**Front axle: 8,000 lb x 15/60 = 2,000 lbRear axle: 32,000 lb x 30/60 = 16,000 lb*Front axle: 8,000 lb x 45/60 = 6,000 lbRear axle: 32,000 lb x 30/60 = 16,000 lb15
16 ii) LATERAL EARTH PRESSURE Lateral earth pressure is the pressure that soil exerts in the horizontal plane.The common applications of lateral earth pressure theory are for :such as retaining walls, basements, tunnelsi) the design of ground engineering structuresfoundationii) to determine the friction on the sides of deep16
17 Lateral Support In geotechnical engineering, it is often necessary to prevent lateral soil movements.Braced excavationAnchored sheet pileTie rodSheet pileAnchorCantilever retaining wall
18 Lateral SupportWe have to estimate the lateral soil pressures acting on these structures, to be able to design them.Gravity Retaining wallSoil nailingReinforced earth wall
31 ii) HYDROSTATIC PRESSURE/ WATER PRESSUREIn a fluid at rest, the weight of the liquidwill create a pressure on the surface of a body.This pressure is defined as the hydrostatic pressure.Its depend on density of the liquid and depth.dam structure.Normally consider for marine structure and31
33 engineering structure due to Environmental ForcesForces that acting toengineering structure due toenvironmental factor
34 i) Wind Load Wind Load What it means positive or negative pressures exerted on a house when it obstructs the flow of moving air.generally act perpendicular to the surfaces of the building.
35 i) Wind Load What it affects The significance of the load varies depending on the geographic location of the house, its height, and its roof pitch.have the most significant impact on roof framing, overhangs, and large openings, especially those near building corners.On a larger scale, shear-resisting elements, like the roof, floor framing, and sheathed wall segments (shear walls), are affected by wind loads.Typically, building are designed to resist a strong wind a very long return period, e.g 50 yrs or more.The design wind speed is determined from historical record to protect future extreme wind speeds.
40 ii) EarthquakeAlso known as quake or tremor.Is the result of sudden release of energy in the earth crust that causes seismic waves.Measured with a seismometerThe seismic activity of an area refers to the frequency, type n size earthquake experienced over a period of time.At the earth’s surface, earthquake manifest themselves by shaking and sometimes displacing the ground.
41 ii) EarthquakeWhen a large earthquake epicenter is located offshore, the seabed sometimes suffer sufficient displacement to cause a tsunamiThe shaking in earthquake can also trigger landslide and occasionally volcanic activityAt the earth’s surface, earthquake manifest themselves by shaking and sometimes displacing the ground.
43 iii) Waves LoadA waves is a disturbance that propagates.The impact of a pulsed or wavelike load to an engineering stucture.Commonly used in the analysis of offshore structure, piping and an engineering platform.