What is pre-stressed concrete?

PRE-STRESSED CONCRETE PART 1

Pre-stressing is a way of counteracting the effect of external loads on structure by imposing a state of stresses contrary to the load effects

Pre-stressing has two parts

Pre-Tensioning

Usually straight or harped profiles, mostly used in the precast industry some example would be hollow core slabs, precast beams, Girder beams

Post Tensioning

Any type of profile, can be precast or cast in place
The only basic difference between pre-tensioning and post tensioning is the state of the structural element while the stressing activities are done. In pretension the stressing is applied prior to concreting while in post tensioning the stressing is applied after the concrete is poured and hardened

Further, Post Tensioning is divided in to bonded and unbonded systems; we will get in to this in later days.
Pre-stressing a concrete element has two effect axial and transversal based on the tendon profile and anchorage selected.
We can have one of the three,
Axial (pure pre compression), Eccentrical axial effect, or axial/transversal effect. The later effect is difficult to utilize in pre-tension system

Comments

What is Slump Test of Concrete-Cone Test Procedure | Workability of Concrete

Slump Test of Concrete-Cone Test Procedure | Workability of Concrete Slump test procedure is to determine the workability of concrete. One of the major problems that you had faced in your field work is concrete compaction during mixing.After mix design, you may have doubt, is this design will be ok? Yes, your design willl be ok in terms of strenght point of view of concrete.But the main problem arises when the mixing of fresh concrete, the compaction of fresh concrete will be very tough.In this situation, you can add some plasticizers without affecting your water-cement ratio or cement-aggregate ratio. Before adding plasticizers or superplasticizers to your fresh concrete, you need to check the workability of your concrete.The slump test is used for checking the workability of concrete.Let us check how can we do slump test of fresh concrete. Apparatus used for cone test procedure 1)Measuring scale 2)Tamping rod 3)Base plate 4)Nonporous base plate 5)Mould for slump test. ...

Different methods of road construction in civil engineering

Different methods of road construction in civil engineering 1) Concrete: It is a common option for road construction purposes as they are a solid material and can be used for building walls and local roads. This method is considerably less prone to wear and tear defects like rutting, cracking, stripping loss of texture, and potholes. This is the main reason for its wide usage. 2) Asphalt: This method of construction replacing concrete method in these days. They are very durable, water-resistant and can go more longer then the concrete. The major advantage of asphalt over concrete is its price. Concrete is very expensive as compared to asphalt. Moreover, asphalt includes low noise during pavement and it is easy to handle it for repairing and maintenance. That is why it is widely accepted and used by the people for the purpose of pavement surfacing. 3) Composite: This method is widely used for the maintenance, recycling, and rehabilitation of the roads. The composite m...

Design Requirement of reinforced Concentrate slab

Table Content 1 Effective span for concentrate slab design 2 Limiting stiffness 3 Minimum reinforcement 4 Maximum diameter of bar 5 Distribution reinforcement concentrate for slab design 6 Cover to reinforcement Let discuss briefly '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 1. Effective Span for concrete slab design For simply supported slab Minimum of clear span plus effective depth of slab Center to center...

What’s the difference between m20 and c20 grade concrete?

A concrete of Grade C20 means that the concrete will have a compression resistance of 20 N/mm² per square millimeter in 28 days. Proportion for grade C20. C20 is 1:2:4 (1 part cement, 2 parts fine aggregate, and 4 parts coarse aggregate.) where as C20 symbolizes a Cylindrical sample in which cement, fine aggregates, coarse aggregates are mixed in such a ratio that its characteristic compressive strength is 20 N/mm² after 28 days of curing. Fig:- Concrete specimen for testing Generally Strength of Cylinder sample= 0.8 x Strength of Cube. example:- M20 is equivalent to C25 M20 means the grade of concrete is defined as the minimum strength of concrete after 28 days. For the M20 Grade of concrete, The letter ‘M’ refers to the mix, and 20 represents the characteristic strength of concrete in MPa or N/mm². The specified characteristic strength of concrete is determined for 150mm size cube at 28 days. The Characteristic Compressive strength of concrete is defined as the strength of conc...

WHAT ARE THE DESIGN PROCEDURES FOR A BUILDING FOUNDATION?

DESIGN PROCEDURES FOR A BUILDING FOUNDATION 1. DECIDE THE LOCATION OF COLUMNS & FOUNDATION AND TYPE OF LOADS ACTING ON THEM.(E.X DEAL LOAD, LIVE LOAD OR WIND LOAD) 2. ESTIMATE ALLOWABLE BEARING PRESSURE OF SOIL USING GROUND INVESTIGATION REPORT. 3. DECIDE DEPTH OF FOUNDATION 4. CALCULATE FOUNDATION AREA 5. DETERMINE VARIATION IN VERTICAL STRESSES 6. CALCULATE SETTLEMENT 7. COST CONTROL 8. CONSIDER TIME 9. VARIATION IN GROUND CONDITION 1. DECIDE THE LOCATION OF COLUMNS & FOUNDATION AND TYPE OF LOADS ACTING ON THEM.(E.X DEAL LOAD, LIVE LOAD OR WIND LOAD) On the building plan, the position of columns and load bearing walls should be marked, and any other induced loading and bending moments. The loads should be classified into dead, imposed and wind loading, giving the appropriate partial safety factors for these loads. 2. ESTIMATE ALLOWABLE BEARING PRESSURE OF SOIL USING GROUND INVESTIGATION REPORT. From a study of the site ground investigation (if available), th...

Shear cap vs drop panel

Shear cap vs drop panel Flat slab design is usually associated with punching shear. In order to reduce the shear stress induced around columns designers usually increase the slab thickness near the column. This increase in thickness in the vicinity of columns is usually called " drop panel ". Is it technically correct to call every thickness increase around columns drop panel? The answer to this question is NO! And let's see an article from ACI 318-14 to arrive at a correct naming/term. drop panel - projection below the slab used to reduce the amount of negative reinforcement over a column or the minimum required slab thickness, and to increase the slab shear strength. shear cap - projection below the slab used to increase the slab shear strength shear caps (popularly called shear heads) are commonly used, especially when the transverse reinforcement does not give the required load capacity. The second advantage of using the shear heads is th...

What is The Difference Between Expressway, Highway, Motorway, Causeway, And Freeway

The Difference Between Expressway, Highway, Motorway, Causeway, And Freeway Various road terminologies are bound to be used without proper or thorough information or enlightenment on the reasons behind such terminologies. Roads come in different types and for different utilization. 1. Expressway. An expressway is a wide road which is targeted at fast moving traffic. Unlike many other roads on the list, the expressway features multiple demarcated lanes which could also include a service lane. The point of the expressway is to promote smooth movement of traffic by dedicating lanes for vehicles about to use the intersections. As earlier stated, most expressways include a service lane. This auxiliary lane is meant for vehicles about to access a street or an intersection. The purpose of the service lane is so that these cars do not disturb the rest of the cars navigating the major roads on the expressway. 2. Highway. Highway is a term...

Civil engineering board and affiliate programs

Search This Blog