What Is The Purpose Of Hydro graphic Surveying?

What Is The Purpose Of Hydro graphic Surveying?

Hydro graphic survey is the science of measurement and description of features which affect maritime navigation, marine construction, dredging, offshore oil exploration/offshore oil drilling and related activities.

What Is A Tacheometer?

Tacheometry, from the Greek "quick measure", is a system of rapid surveying, by which the positions, both horizontal and vertical, of points on the earth's surface relatively to one another are determined without using a chain or tape or a separate leveling instrument.

Civil Engineering Shorts Question

1.  What Does It Mean To Survey A Boat?
   Answer :
   Basically, it is a detailed inspection of a boat, hopefully done by a qualified, diligent, intelligent and honest surveyor, for the purpose of determining its current condition and seaworthiness.
2. What Is A Chartered Quantity Surveyor?
   Answer :
   Members and Fellows of the RICS entitled to use the designation (and a number of variations such as "Chartered Building Surveyor" or "Chartered Quantity Surveyor" or "Chartered Civil Engineering Surveyor" depending on their field .

What Is An Automatic Level?

What Is An Automatic Level?



A dumpy level, builder's auto level, leveling instrument, or automatic level is an optical instrument used to establish or verify points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and to transfer, measure and set heights.

How to determine the size of elastomeric bearings?

How to determine the size of elastomeric bearings?

 For elastomeric bearing, the vertical load is resisted by its compression while shear resistance of the bearing controls the horizontal movements.

The design of elastomeric bearings are based on striking a balance between the provision of sufficient stiffness to resist high compressive force and the flexibility to allow for translation and rotation movement. The cross sectional area is normally determined by the allowable pressure on the bearing support. Sometimes, the plan area of bearings is controlled by the maximum allowable compressive stress arising from the consideration of delamination of elastomer from steel plates. In addition, the size of elastomeric bearings is also influenced by considering the separation between the structure and the edge of bearing which may occur in rotation because tensile stresses deriving from separation may cause delamination. The thickness of bearings is designed based on the limitation of its horizontal stiffness and is controlled by movement requirements. The shear strain should be less than a certain limit to avoid the occurrence of rolling over and fatigue damage. The vertical stiffness of bearings is obtained by inserting sufficient number of steel plates. 

What are the advantages of assigning the central pier and the abutment as fixed piers?

 What are the advantages of assigning the central pier and the abutment as fixed piers? 

For abutment pier to be assigned as fixed pier while the bridge is quite long, the longitudinal loads due to earthquake are quite large. As the earthquake loads are resisted by fixed piers, the size of fixed piers will be large and massive. In this connection, for better aesthetic appearance, the selection of abutment as fixed piers could accommodate the large size and massiveness of piers. Normally abutments are relatively short in height and for the same horizontal force, the bending moment induced is smaller.

For the central pier to be selected as the fixed pier, the bridge deck is allowed to move starting from the central pier to the end of the bridge. However, if the fixed pier is located at the abutment, the amount of movement to be incorporated in each bearing due to temperature variation, shrinkage, etc. is more than that when the fixed pier is located at central pier. Therefore, the size of movement joints can be reduced significantly. 

In bridge widening projects, the method of stitching is normally employed for connecting existing deck to the new deck. What are the problems associated with this method in terms of shrinkage of concrete?

In bridge widening projects, the method of stitching is normally employed for connecting existing deck to the new deck. What are the problems associated with this method in terms of shrinkage of concrete?

In the method of stitching, it is a normal practice to construct the widening part of the bridge at first and let it stay undisturbed for several months. After that, concreting will then be carried out for the stitch between the existing deck and the new deck. In this way, the dead load of the widened part of bridge is supported by itself and loads arising from the newly constructed deck will not be transferred to the existing deck which is not designed to take up these extra loads.

One of the main concerns is the effect of stress induced by shrinkage of newly widened part of the bridge on the existing bridge. To address this problem, the widened part of the bridge is constructed a period of time (say 6-9 months) prior to stitching to the existing bridge so that shrinkage of the new bridge will take place within this period and the effect of shrinkage stress exerted on the new bridge is minimized.

Traffic vibration on the existing bridge causes adverse effect to the freshly placed stitches. To solve this problem, rapid hardening cement is used for the stitching concrete so as to shorten the time of setting of concrete. Moreover, the stitching work is designed to be carried out at nights of least traffic (Saturday night) and the existing bridge may even be closed for several hours (e.g. 6 hours) to let the stitching works to left undisturbed.

Sometimes, longitudinal joints are used in connecting new bridge segments to existing bridges. The main problem associated with this design is the safety concern of vehicles. The change of frictional coefficients of bridge deck and longitudinal joints when vehicles change traffic lanes is very dangerous to the vehicles. Moreover, maintenance of longitudinal joints in bridges is quite difficult.   

In incremental launching method of bridge construction, what are the measures adopted to enhance sufficient resistance of the superstructure during the launching process?

In incremental launching method of bridge construction, what are the measures adopted to enhance sufficient resistance of the superstructure during the launching process?

• During the launching process the leading edge of the superstructure is subject to a large hogging moment. In this connection, steel launching nose typically about 0.6-0.65 times span length is provided at the leading edge to reduce the cantilever moment. Sometimes, instead of using launching nose a tower and stay system are designed which serves the same purpose. 

• The superstructure continually experiences alternative sagging and hogging moments during incremental launching. Normally, a central prestress is provided in which the compressive stress at all points of bridge cross section is equal. In this way, it caters for the possible occurrence of tensile stresses in upper and lower part of the cross section when subject to hogging and sagging moment respectively. Later when the whole superstructure is completely launched, continuity prestressing is performed in which the location and design of continuity tendons are based on the bending moments in final completed bridge condition and its provision is supplementary to the central prestress. 

• For very long span bridge, temporary piers are provided to limit the cantilever moment.  

What is “preset” during installation of bridge bearings?

What is “preset” during installation of bridge bearings?

 “Preset” is a method to reduce the size of upper plates of sliding bearings in order to save the material cost. The normal length of a upper bearing plate should be composed of the following components: length of bearing + 2 x irreversible movement + 2 x reversible movement. Initially the bearing is placed at the mid-point of the upper bearing plate without considering the directional effect of irreversible movement. However, as irreversible movement normally takes place at one direction only, the bearing is displaced/presetted a distance of (irreversible movement/2) from the mid-point of bearing in which the length of upper plate length is equal to the length of bearing + irreversible movement + 2 x reversible movement. In this arrangement, the size of upper plate is minimized in which irreversible movement takes place in one direction only and there is no need to include the component of two irreversible movements in the upper plate. Note: “Preset” refers to the displacement of a certain distance of sliding bearings with respect to upper bearing plates during installation of bearings.

Civil engineering Short Question

What is the purpose of the gap in the road on this bridge?

Purpose of the gap in the road is to allow the road to expand and contract with temperature changes without causing damage or deformation to the road.

What is a projection line?

Projection line is the way, in which the earth is shown on a flat piece of Paper.

What are moment of inertia and its importance in civil engineering?

The moment of inertia measures the opposition any kind of body will have against a certain momentum (along that same axis) trying to rotate that body.

What is the absolute pressure scale?

Absolute pressure is calculated from a vacuum (0 PSI) and atmospheric pressure is14.7PSIa or 14.7 PSI above a vacuum 1PSI on a tire pressure gauge is called 1PSIg = 15.7PSIa 10PSIg=24.7PSIa 100PSIg=114.7PSIa etc.

What is diversion tunnel in a dam?

When a dam is to be built, a diversion tunnel is usually bored through solid rock next to the dam site to byPAss the dam construction site. The dam is built while the river flows through the diversion tunnel.

How do you maintain water pressure?

If you have water pressure and wish to maintain it, do not cause flow in the line, which will reduce pressure due to friction. To keep pressure up, reduce friction by increasing the line size or eliminating some other restriction.

 Why does the pressure increase under soil?

Soil pressure increases with depth due to the overburden or self-weight of the soil and due to loads imposed upon the soil.
For example, the pressure variation below the depth of soil is linear and the relation is given by pressure = unit wt * depth. As depth increases, there will be a linear increase in the soil pressure.

Why should curing not be done by pounding and polythene sheets?

Why should curing not be done by pounding and polythene sheets?

The primary purpose of curing is to reduce the heat loss of concrete that is freshly placed to the atmosphere and in order to reduce the temperature gradient across the cross-section of the concrete. Pounding is not preferred for curing as this method of thermal curing is greatly affected by cold winds. In addition to that in pounding large amounts of water is used and has to be disposed off from the construction sites. Polythene sheets are used on the basis that it creates an airtight environment around the concrete surface henceforth reducing the chances of evaporation over fresh concrete surfaces. But the usage of polythene can be a drawback as it can be easily blown away by winds and also the water lost by self-desiccation cannot be replenished.

Why should pumping be not used in case of concreting works?

Why should pumping be not used in case of concreting works?

During the pumping operation the pump exerted pressure must overcome any friction between the pumping pipes and the concrete, also the weight of the concrete and the pressure head when the concrete is placed above the pumps. Since only water is pump able, all the pressure generated is by the water that is present in the concrete. The major problem due to pumping are segregation effects and bleeding. In order to rectify and reduce these effects, generally the proportion of the cement is increased in order to increase the cohesion , which leads to the reduction of segregation and bleeding. Also if a proper selection of the aggregate grading can vastly improve the concrete pump ability.

What reinforcements are used in the process of prestressing?

What reinforcements are used in the process of prestressing?

The major types of reinforcements used in prestressing are:
> Spalling Reinforcement: The spalling stresses leads to stress behind the loaded area of the anchor blocks. This results in the breaking off of the surface concrete. The most likely causes of such types of stresses are Poisson`s effects strain interoperability or by the stress trajectory shapes.
> Equilibrium reinforcements: This type of reinforcements are required where several anchorages exist where the prestressing loads are applied in a sequential manner.
> Bursting Reinforcements: These kinds of stresses occur in cases where the stress trajectories are concave towards the line of action of load. In order to reduce such stresses reinforcements in the form of bursting is required.

Why are steel plates inserted inside bearings in elastomeric bearings?

Why are steel plates inserted inside bearings in elastomeric bearings?

In order to make a elastomeric bearing act/ function as a soft spring it should be made to allow it to bulge laterally and also the stiffness compression can be increased by simply increasing the limiting amount of the lateral bulging. In many cases in order to increase the compression stiffness of the bearing the usage of metal plates is made. Once steel plates are included in the bearings the freedom of the bulge is restricted dramatically, also the deflection of the bearing is reduced as compared to a bearing without the presence of steel plates. The tensile stresses of the bearings are induced into the steel plates. But the presence of the metal plates does not affect the shear stiffness of the bearings.

What do you understand by “preset” during the installation process of bridge bearings?

What do you understand by “preset” during the installation process of bridge bearings?

During the installation of bridge bearings the size of the upper plates is reduced to save the material costs. This process is known as preset. Generally the upper bearing plate comprises of the following components:
> Length of bearing
> 2 x irreversible movement.
> 2 x reversible movement.
The bearing initially is placed right in the middle point of the upper bearing plate. No directional effects of irreversible movement is considered. But since the irreversible movement usually takes place in one direction only the displaced direction is placed away from the midpoint. In such cases the length of the upper plate is equal to the length of the length of the bearing + irreversible movement + 2 x reversible movement.

Describe briefly the various methods of concrete curing.

Describe briefly the various methods of concrete curing.

Curing is the process of maintaining the moisture and temperature conditions for freshly deployed concrete. This is done for small duration of time to allow the hardening of concrete. The methods that are involved in saving the shrinkage of the concrete includes:
(a) Spraying of water: on walls, and columns can be cured by sprinkling water.
(b) Wet covering of surface: can be cured by using the surface with wet gunny bags or straw
(c) Ponding: the horizontal surfaces including the slab and floors can be cured by stagnating the water.
(d) Steam curing: of pre-fabricated concrete units steam can be cured by passing it over the units that are under closed chambers. It allows faster curing process and results in faster recovery.
(e) Application of curing compounds: compounds having calcium chloride can be applied on curing surface. This keeps the surface wet for a very long time.

What are the steps involved in the concreting process, explain?

What are the steps involved in the concreting process, explain?

The major steps involved in the process of concreting are as follows:
1. Batching
2. Mixing
3. Transporting and placing of concrete
4. Compacting.

> Batching: The process of measurement of the different materials for the making of concrete is known as batching. batching is usually done in two ways: volume batching and weight batching. In case of volume batching the measurement is done in the form of volume whereas in the case of weight batching it is done by the weight.
> Mixing: In order to create good concrete the mixing of the materials should be first done in dry condition and after it wet condition. The two general methods of mixing are: hand mixing and machine mixing.
> Transportation and placing of concrete: Once the concrete mixture is created it must be transported to its final location. The concrete is placed on form works and should always be dropped on its final location as closely as possible.
> Compaction of concrete: When concrete is placed it can have air bubbles entrapped in it which can lead to the reduction of the strength by 30%. In order to reduce the air bubbles the process of compaction is performed. Compaction is generally performed in two ways: by hand or by the use of vibrators.

Civil Engineering short Questions

What are the main reasons of building collapse?
There are several reasons for building collapse. Passage of time is the main reason. Also, weak foundations, natural calamities like earthquakes, hurricanes, etc., are the major reasons for building collapse. Bombing and destruction is also another major reason.

State the applications of modulus of elasticity.
Modulus of elasticity is related to the flexibility of the material. The value of modulus of elasticity is pretty important in case of deflection of different materials used in building construction.

How are the freeway bridges built?
The traffic that is likely to go over the bridge at a time is estimated and the cement, rocked with rebar stanchions is placed over the freeway to build a bridge. Off-ramp from freeway to the bridge and on-ramp from the bridge to the freeway are constructed. Cement slabs are used to build a platform.

What is the basic difference in absorption, adsorption, and sorption?
Absorption refers to the phenomenon where an atom, molecule or ions enter any bulk phase like gas, solid or liquid. Absorption refers to the phenomenon where energy of photon is transferred to other entity.
Adsorption is similar to absorption. It refers to the surface rather than a volume. Adsorption takes place when the gas or liquid solute accumulates on the surface of solid. A substance diffuses in liquid or solid to form a solution.

Civil Engineering Short Questions

How do you measure concrete? 
Cubic feet, Cubic yards, Cubic Meter


Which is stronger solid steel rod or hollow steel pipe? 
On a per pound basis, steel pipe is stronger in bending and is less likely to buckle in axial compression.

What is braced excavation all about? 
Excavations are braced to prevent the cave-in of surrounding unstable soil.

What is the meaning of soil reinforcement? 
Soil reinforcement is the act of improving soil strength to enable it support or carry more load.

Two common examples are:

a) Mixing a soil amendment such as lime into weak clayey soil and re-compacting to improve soil-bearing capacity (often done under the road base in highway construction)

b) Installing plastic or composite webbing layers (called geo-grid material) alternating with compacted soil to produce a stronger sloped soil structure (often done on steep roadway embankments to improve strength and stability)

What is aggregate? 
Aggregate is the component of a composite material used to resist compressive stress.

What year was the keystone power plant in Indiana County constructed? 
1967 began commercial operation on unit 1.

What is the force exerted by the Tacoma narrows bridge? 
The force exerted to the Tacoma narrows bridge was initially the wind resistance. The wind resistance caused the whole bridge to act as a system with forced vibration with damping.

Explain the concept of built area and super built-up area.

Explain the concept of built area and super built-up area. 

Built up area includes the carpet area as well as any space occupied by walls, pillars, and ducts. In most cases, the built-up area is calculated as an excess of 10% of the carpet area. 

The super built-up area covers the built-up area as well as any areas that used by building amenities such as life passages, lobby, stairs, gym, clubhouse, etc. 

Describe the various types of slump test indications.

Describe the various types of slump test indications. 

Slump tests are initiated to empirically measure the consistency of fresh concrete before it sets. They can also be used to check for an improperly mixed batch of concrete as well. There are three different types of slumps that occur in slump tests listed as below: 

• True Slump 
• Shear Slump 
• Collapse Slump