Posts

Video from my YouTube channel

Subscribe to My You tube channel

AASHTO classification of soil

By -
Image
Classifying the soil considered a significantly important in road engineering as it will help the Engineer in understanding the soil behavior under the loads, change in moisture and the traffic volume. AASHTO classification is one of the most used soil classification system in road projects.  This system is used mainly to evaluate the soil used in road construction especially materials used for road Embankment, Subgrade, subbase. The AASHTO classification system doesn't relies on the simple visual description, it relies mainly on lab testing such as sieve analysis and atterberge limits to classify the soil.  AASHTO classification system used mainly to classify soil according to their expected performance as a road construction materials. In road engineering, the road subgrade support the road pavementayers above it. If the road Subgrade is weak or highly compressible, etc this will result in road settlement, cracks formation, Formation of rutting and low performance of Pavemen...
Post a Comment
Read more

Temperature load

By -
Temperature load shall be considered by the designers as it can excert significant stresses on structurs. Unlike dead and live load, the temperature load is not generated due to material or people weight. It is generated due to temperature changes that will cause structure elongation and contraction.  Temperature load is the stress generated in the structure due to change in structure temperature. This effects occurs due to daily weather variation or seasonal variations or due to direct exposure to sun or fire or due to the temperature difference between the construction and operation stages.  No stress will be generated for structure element that can move or on other word accommodate the structure expansion and contraction due to temperature effects. But if the structure elements movement is restricted, then the structure element will resist the changes in size which will generate stresses in the structure.  Example, a very good example of the effects of temperature load...
Post a Comment
Read more

Road servicibility level

By -
Road servicibility level is considered as an Engineering standard used to evaluate road ability to service the traffic safely, comfortably and efficiently. The government will use the road serviceability level records and available data to determine the priorities in maintenance to reduce vehicles wear and prevent traffic jam.  The evaluation of a road will be based mainly on the physical condition of the road pavement and the flow of traffic: 1.Pavement Condition: The Present Serviceability Index (PSI)  The PSI isolate the physical condition of road pavement. This index was developed based on a wide and extensive transport road. It has a numerical scale to evaluate the pavement physical condition and it ranges from 0 to 5. 1-Excellent (5): Excellent pavement surface, smooth and free from defects. This level is ideal therotical because new road rarely get the score of 5 due to construction tolerances.  2-very good (4.0-4.9): New road or newly reinstated roads that provide...
Post a Comment
Read more

Traffic Signal Phasing: How Intersections Manage Vehicle and Pedestrian Movement

By -
 Traffic signal phasing is one of the most important concept in traffic Engineering. The traffic signal phasing concept define how the traffic signal divide the time among the different traffic movement at an intersection. On other word, it determines who moves, when moves and who will wait. Well deisgn signal phasing plan will enhace safety, reduce the delay and improve the traffic flow at an intersection. Furthermore,it will help in organizing the traffic movement at an intersection and prevent the conflict between vehicles, pedestrian and cyclist. -What Is a Traffic Signal Phase? Traffic signal phase is a specific part of the signal cycle which allows one movement or more to take place.  For example, in a four-leg intersection. The traffic could allow the traffic movement from north to south. While the traffic movement must be idle from the east to west. Then another phase would take place and allow the traffic movement from east to west, while traffic movement stopped from...
Post a Comment
Read more

Welding Techniques and Quality Inspection for Structural Steel Applications

By -
Image
Types of Welding There are different types of welding used in steel structures, one of the most common being arc welding . In arc welding, the process uses a welding rod (electrode) to generate heat through an electric arc. The heat melts both the base metal and the tip of the electrode, allowing molten droplets of the electrode to deposit and fuse with the base metal. During this process, the weld area must be protected from atmospheric contamination. This protection is provided by inert gas or a vapor shield produced from the burning of the electrode coating. If this protective gas shield is not present, oxygen and nitrogen from the air may enter the molten weld metal, resulting in porosity , reduced toughness, and a brittle weld . Electrodes used in arc welding are classified into two types: Heavily-coated electrodes : Commonly used for structural welding, as they provide adequate shielding to protect the molten weld pool. Lightly-coated electrodes : Provide minimal shieldi...
Post a Comment
Read more

Videos from My Youtube channel

Popular posts from this blog

Rebar Splicing and Overlapping — ACI 318-19 Requirements Explained

By -
Image
Reinforcement splicing or overlapping is a fundamental requirement in reinforced concrete structures. Because reinforcement bars (rebars) are manufactured in limited standard lengths—typically 12 m —it becomes necessary to splice or overlap them to achieve the required continuity in structural members. The main purpose of a splice is to ensure smooth stress transfer between adjacent bars through the surrounding concrete. The overlap length, commonly known as the splice length , must be long enough to safely transfer the tensile stresses from steel to concrete without causing bond failure. It is recommended to avoid splicing in high-stress zones such as areas of maximum moment, and to stagger the splices to prevent congestion and reduce stress concentration. The ACI 318-19 providing the following recommendatin and requirement for the lap splicing: 1. Splice Limitation by Bar Size Lap splicing is not permitted for reinforcement bars larger than 36 mm in diameter. 2. Non-Contact L...
Read more

stress-strain diagram for aluminium alloy and rubber

By -
Image
figure no:1 showing the stress-strain diagram for aluminum alloy. we can notice from the stress-stress diagram that aluminum has a considerable ductility. despite the absence of explicit yield point as in structural steel . the initial portion of the stress-strain curve is linear with a recognizable proportional limit. the proportional limit for aluminum alloy ranges from 70 to 410 Mpa (10 to 60 Ksi). aluminum alloy undergoes large strain before failure. ultimate stress ranges from 140 to 550 Mpa (20 to 80 Ksi). construction management: concrete construction bridge construction:How to become a bridge engineer Figure-1 Yield stress for aluminum alloy can be determined by drawing offset line parrel to the linear portion of the stress-strain curve. the straight line offset by a standard strain such as 0.002. the intersection point with the stress-strain curve is the point of yield stress. figure no:2 illustrates the concept of offset method. yield stress acquire...
Read more

Binding wire for steel reinforcement

By -
Image
  Binding wires are used to tie steel bars together. These wires are playing a significant role in maintaining the reinforcement stability and rigidity. Wires are used to tie the steel bars at intersections points. By tying the steel bars together, we ensure that the steel bars will not move from their locations during construction or during the time of concreting. In slabs, binding wires are used to tie longitudinal and transverse bars together. In columns, it is used to tie vertical bars with stirrups.   Figure 1 There are various types of binding wires such as  Black annealed baling wire, Stainless Steel Binding Wire, and PVC coated binding wires.  Black annealed baling wire used to tie black steel. The popular size for black wire ranges from 16 to 22 gauges. Stainless steel binding wires are used to bind stainless steel reinforcement. Stainless steel reinforcement is used in a harsh environment where the black steel gets rusted quickly. Therefore, stainless ...
Read more

Pile cap

By -
Image
Pile cap used to transfer the loads from superstructure to the piling. The pile cap is thick concrete mat rests on piles. It is part of the foundation and used to distribute the loads over the piles. Piles used when the soil bearing is not enough to carry loads of the structure. Figure 1  construction management: concrete construction bridge construction:How to become a bridge engineer Pile cap construction procedure Excavation around piles: After 7 days of the casting of the pile the concrete will gain approximately, 70% of it is compressive strength. The soil around piles will be removed to the required levels and dimension that allows construction of the pile cap. A step shall be made if the excavation is more than 1.5 m to prevent soil collapse. Figure 2 Pile head cutting: Concrete will be removed up to cut off level. If concrete under the cut off level is unsound. It shall be removed, and the pile will be repaired...
Read more

Non-Working Pile Testing and Static Compression Load Test

By -
Image
Purpose of Non-Working Piles Non-working piles are constructed at the beginning of the project to evaluate soil bearing capacity and determine the maximum settlement. These piles are loaded up to twice the working load. Based on the test results, the pile length may be adjusted. If the measured settlement exceeds the allowable limit, the pile length will be increased accordingly. construction management: concrete construction bridge construction:How to become a bridge engineer Static Compression Load Test The static compression load test provides insight into how the pile responds to loading. Settlement is measured at different load increments to determine the appropriate pile design length. The maximum applied load is typically twice the working load (2 × working load) or as specified by local standards. The following steps outline the testing procedure: A. Steel Cage Preparation The steel reinforcement cage is prepared in accordance with the approved shop drawings. ...
Read more

Prestressing stands debonding

By -
Image
  Prestressing bridge concrete beams contributes to resisting the tensile stresses caused by the traffic loads and the beam's weight. Stressing concrete has various benefits, such as increasing concrete members' capacity, reducing the concrete member section, and increasing the span lengths for structures such as bridges and buildings. However,  The stressing of bridge beam ends can result in unwanted cracks. Therefore AASHTO calling for debonding a specific portion of strands at the beam end to minimize the stresses and reduce cracks. Figure 1 Debonding is achieved by wrapping the strands at the end of the beam with plastic. Wrapping the strand with plastic wrapping will prevent the strands from bonding with concrete, thus avoid transferring unwanted stress to the beam end. As a result, the unwanted cracks will be prevented by reducing the stress levels at the end of the beam.  
Read more

Bridge Top slab

By -
Image
Once the curing of bottom slab and web completed. The construction of the top slab will begin. Top slab usually has a small width, therefore using cup-lock as a supportive system (falsework) will be enough. Top slab construction is simple and can be done in a shorter time compared to web and bottoms slab. The reinforcement for the top slab usually consists of four layers of reinforcement — two layers in each direction. The reinforcement in short direction will be more. As we know, the loads will be transferred in a short direction. Figure 1 construction management: concrete construction bridge construction:How to become a bridge engineer After the erection of falsework system. Primary beams will be installed at intervals in the short direction. Intervals between the primary beam shall be matching the calculation by the designer. Above the primary beam and in the longitudinal direction, the secondary beam will be fixed to support the formwork for top slab. ...
Read more

Fire resistive construction-firewalls

By -
Image
The fire-resistive construction method will involve the designing and construction of fire resisting elements such as firewalls, fire barriers, fire partitions, smoke barriers, and smoke partition. The purpose of these components is to restrict the spread of fires between building units. Firewalls should be continuous from the foundation to the building roof, and it should have sufficient stability to resist the collapsing if the construction on either side collapse. Firewalls used to separate a structure into multiple units, which reduce the severity and consequences of fires by limiting the fire in one area and prevent the spreading of the fires to other structures area. Fire barriers and partitions are interior walls used to sub-divide the portion of a building that concealed by firewalls into smaller areas. Fire barriers and walls will be supported by the adjacent structure. They will prevent the heat flows within the area concealed by firewalls, which gives the residents suf...
Read more

Nominal maximum size of coarse aggregate

By -
Image
Concrete is a widely used material. Reinforced concrete structures can be found everywhere. The main reason behind the popularity of reinforced concrete structure is the high strength and the long life span of these structures. Concrete and steel are combined to produce reinforced concrete. Concrete is good at compression while steel good at tension. Concrete and steel form a perfect combination to resist loads imposed on the structure. Concrete is a composite material composed of cement, coarse aggregate, fine aggregate, and water. Admixtures can be used to enhance concrete properties. A concrete mix consists of almost 65% aggregates. Aggregates are classified into fine and coarse aggregates. Since the aggregates form the majority of a concrete mix. The quality of aggregates can greatly affect the strength and durability of concrete. Aggregates can be natural or crushed aggregates. Used aggregates should be strong, hard, and should not contain a large amount of organic matter or harmf...
Read more

Repairing of concrete bulging

By -
Image
Improper designing and installation of formwork for a concrete member can result in concrete Bulging. During the placing and compacting of concrete, forms may deflect largely in the weak areas. The deflection of forms will cause concrete to expand at this location, and this known as concrete Bulging. Concrete Bulging will spoil the appearance of a concrete member. Therefore we should always ensure that the forms are appropriately installed, and it is sufficiently supported to resist the concrete during placing and compacting. Bulging should be repaired in case we couldn't avoid it. The solution of concrete Bulging, offset, or surface irregularities are surface grinding. However, excessive surface grinding can weaken the concrete.  Figure 1 If the bulging or surface irregularities are small, grinding of concrete surface will be sufficient to remove surface irregularities. If the Bulging of concrete is significant, then the concrete should be chipped, and the surface...
Read more