Role of post tensioning in construction of efficient infrastructures

With the advancement in science, our world is evolving and so does the infrastructure. The demand of smart infrastructure has increased in recent decades which demand an upgraded quality of concrete so that the structure can support any load beyond its own dead weight. Many structures have collapsed in past because

• The concrete structure couldn’t bear the oversized load e.g. I-5 Skagit River Bridge accident in 2013

• It was structurally too rigid to withstand the damaging factors like strong winds e.g. I-35W Mississippi River Bridge collapse in 2007

• Frequent accidents where vehicles hit the supporting post like boat colliding with the foundation of the bridge e.g. 14th Street Bridge accident in 1982

• Design errors and material used in the construction e.g. Tacoma Narrows Bridge accident in 1940.

• Earthquakes causing damage to the structure e.g. San Francisco – Oakland Bay Bridge collapse in 1989

We have learned from these accidents that if the design and construction quality of any infrastructure is improved then accidents like bridge failures can be prevented. Post tensioning technique which uses prestressed post tensioned tendons to reinforce concrete structures has revolutionized the construction of infrastructures.  it offers many advantages over regular construction technique. Some of the features of post tensioning are following as

• It offers flexibility to the structure means if the structure tend to sag or deflect under the live load then also the concrete structure won’t crack.

• It has lowered down the material and maintenance cost

• It has also reduced the construction time because it allows longer spans in a structure without building supports.

• It increases the tensile strength and load bearing capacity of the structure thus making it durable and long lasting.

• It can also resist the environmental factors e.g. it can withstand stronger winds or earthquakes as it is structurally flexible.

How post tensioning improves the quality of concrete?

Post tension tendons made from high tensile steel, carbon fibre or aramid fibre is placed within or adjacent to concrete volume to provide flexibility to the concrete structure. When extra pressure is applied by the living load, the post tension tendons share the load and prevent cracking in the concrete member.

Once the concrete is stressed along with tendons, it becomes high strength concrete and can withstand tension forces. Post tension tendons and prestressed concrete is widely used in building huge structures like bridges, skyscrapers, dams, silos and tanks, nuclear containment structures and industrial pavement etc. Prestressed concrete with post tension tendons is much better option than the reinforced concrete because of its improved performance which allows reduced structural thickness and longer span which is essential for building complex structures.

What is the constraint while using post tension tendon in concrete structures?

The biggest advantage of post tensioning is lack of cracking and ability to span large spaces without any support. Post tension slabs can be placed or stamped just like reinforced concrete slab and the surface can be overlaid or stained. It is important to consider that the post tensioned concrete should not be cut or drilled because once a post tension tendon is cut down, it is difficult to repair or replace.

It is very difficult to find any damage to the post tension tendons from the surface as they are deeply embedded inside the concrete member. Infrastructure Preservation Corporation (IPC) provides the first post tension tendon scanning system which utilizes the Electrical Capacitance Tomography (ECT) to perform a MRI like assessment of the post tension tendons. This system is referred as “TendonScan” and it can provide accurate information about any deterioration or section loss like corrosions, voids, bleeding grout and any other problem caused to the tendons so that the decision makers can take appropriate action for repairs, in budget and on time.

To know more about TendonScan, our other products and services, you can visit our website https://www.infrastructurepc.com/ or contact us at info@infrastructurepc.com.

Drones (UAS) for Bridge Inspections A New Approach

Drones The approach to utilizing Unmanned Aerial Systems (UAS) for bridge inspections in regards to incorporating same into the realm of structural bridge inspections is long overdue and is welcomed due to the system’s ability to access areas of bridge which would normally require the archaic and oft utilized approach of requiring the incorporation of travel lane closures, costly under-bridge access equipment, and the requirements of conducting bridge inspections at night as not to interrupt traffic flow.

State by state departments of transportation are researching the viability of drone inspections on our nations infrastructure.  Using a drone for Bridge inspection services add a valuable resource in the bridge inspectors toolbox.

Whereas, for safety reasons, a UAS (being a machine) will never be incorporated and utilized over live traffic, however, its ability to provide stand-off positioning adjacent and parallel to the bridge structure for deck inspections is unsurpassed.

A UAS can be used quickly and efficiently to conduct a full bridge structure inspection, which in turn, will identity areas which might require a more hands-on and thorough inspection of structural deficiencies revealed.   The cost savings enjoyed by the bridge owner who selects an inspection consultant which utilizes a UAS inspection approach and program, versus the under-bridge equipment method, is practically infinite. 

DETAILED REQUIREMENT FOR DRONE USE IN BRIDGE INSPECTIONS 

The UAS will be fitted with high resolution video cameras which will transmit real-time inspection views and inspection progress, infrared thermography (IR) cameras which reveal delamination locations and perimeters of same in concrete surfaces, and a laser-based measuring device which will denote the width of structural cracks discovered.  All the data will be transmitted, via telemetry; to the ground-based Command Center System which will in turn collect and archive all data received for submittal to, and reviewed by, the bridge owner, which will be used for future comparison and reference.

The above information and data will be incorporated into a final bridge inspection report to be submitted to the bridge owner.  At that time, a meeting between the bridge owner and the inspection will be conducted to discuss findings of the UAS inspection, what these findings mean in relation to the Health Index of the bridge, and then further discuss the need for work order-driven repair approaches and requirements.

This information shall be kept and secured by the UAS inspection consultant at all times, and if required and directed by the bridge owner upon their receipt of all bridge inspection related data, the UAS inspection consultant shall delete all files related to the bridge inspection.    

INCORPORATING UAS INTO BRIDGE INSPECTIONS

The incorporation of UASs into viable bridge inspection

procedures is a long overdue and very welcomed approach, since all of us who have been involved in onsite bridge inspection projects for many years know the inherent dangers required for us to perform our duties in regards to maintaining the trust of the traveling public that the nation’s bridges are safe.  Instead of human inspectors risking life, limb and injury to perform their duties in avenues of active traffic, rappelling structural bridge members, and accessing areas on a bridge by massive manlifts and/or under-bridge machines, we now have what was once considered insurmountable, to now having the option of machines performing these duties in our stead.  One can replace a UAS easily, but a human life is irreplaceable. 

In all likelihood, and until the UAS manufacturers can provide a fool-proof and nearly indestructible machine which will be guaranteed to be free of any and all malfunctions, a UAS will not replace the hands-on inspection requirements related to Fracture Critical members of a bridge nor will a UAS be able to access the tight connections within a through-truss bridge nor a deck-truss bridge, but many areas are now within easy reach by utilizing UASs safely. 

For more expert information on bridge inspections using drones contact info@infrastructurepc.com.

Introduction to Pole Scan (A high mast light pole inspection Service)

High Mast Light Poles are installed at our busiest intersections as well as on ramps and off ramps of most highway systems. . It is a tall pole at least 30 metres (98 feet) high and the lighting system consists of several lighting fixtures mounted around the luminaries ring at the top of it. The pole itself is built in sections with each section inserted into the other and ground at the base with anchor bolts that go 3-4 feet into the ground.  The HMLP “High mast light pole” needs to remain sturdy and withstand gale force winds for years without rusting apart or falling.

Maintenance inspections of the high mast light pole are conducted every 5 years and typically done by lowering the luminaries ring from the mast head to its base by using a motor and winch but inspection of the pole surface and seams is a difficult task. Traditional pole inspection involves a visual inspection of the pole from the ground by an inspector.

Infrastructure Preservation Conservation (IPC) has developed a unique High Mast Light Pole inspection service named Pole Scan® which helps the inspector in assessing the light pole and its various components like seams and luminaries for any imperfections from the comfort of his office.

What it is?

It is a robotic high mast light pole inspection system which is remote controlled from a monitoring station. This system offers 100 percent coverage of the entire light pole including the pole surface, seams, luminaries and other components. This advanced system exceeds all FHWA and state requirements for assessment. The inspections are conducted by experienced professionals who are trained to use the technology to provide the department of transportation with much more quantitative data than the traditional manual inspection

Why was it built?

High Mast light Pole inspection from conventional methods is subjective because an inspector examines the pole visually. If two inspectors examine the same pole at the same time then the two outcomes will be different. Moreover, other components of the HMLP like seams and surface are neglected and the potential defects or deteriorations are not properly monitored Some of the components or anomaly’s can be occurring 50-90 feet up or underground and not visible to the human eye. Pole Scan® was built to make subjecting testing a thing of the past and to inspect all the components of the HMLP from every angle providing quantitative data to the department of transportation in order for them to properly allocate their resources to maintain them and extend their service life.

How is it used?

Pole Scan® utilizes Non Destructive Testing methods and robotics technology. A self propelled robotic system is mounted on the pole and it is remotely controlled from the base station. It moves along the length of the pole and records all the details of the surface, seams and other components in form of a high definition video. The recorded data can be analyzed in real time for later analysis. The history is also used for monitoring of the advancement of the any deterioration.

What problem does it solve?

PoleScan® has improved the inspection service of high mast light pole and enhanced the quality of the results. The collected data is used for monitoring of rate of deterioration over time as well as reporting any imperfections in order to properly maintain them.

For more information about IPC and its road and bridge inspection services, you can visit our site https://www.infrastructurepc.com or email us at info@infrastructurepc.com.

What is a post tension tendon?

“Post tensioning is a technique for reinforcing concrete. Post-tensioning tendons, which are pre-stressing steel cables inside plastic ducts or sleeves, are positioned in the forms before the concrete is placed.” Post tension cables in effect allow us to safely build large concrete structures. They allow larger spans, thinner slabs and greater distances between support commons. Post tensioning is used in bridges and box girder structures worldwide including on our bridges, on and off ramps.  Post tensioning makes it possible to build structures that might not otherwise be possible. Because concrete is not flexible it can crack under loads.  Although rebar is used to reinforce the concrete to prevent cracks from growing the concrete can still sag under increased loads. PT or post tension cables are load bearing and can stand large increases in loads bearing up the concrete.

There are many benefits that are gained by using a post-tensioned approach.  It allows for flexibility of design, faster construction and lower material costs. Over the long term, it can reduce maintenance costs and allow for increased loads over time.

Bridges that utilize post tension tendons are able to contain long and clear spans, have few beams and slender members and thinner slabs can be used which is not possible in case of regular bridges. This method reinforces or strengthens the concrete or other material with high strength steel bar or strand which is known as “tendons”. It significantly reduces the building weight and foundation load which is very useful in seismic areas.

Post tension tendons help in construction of complex bridges which has specific geometry requirements such as complex curves and super elevation. Extremely long span bridges can be constructed with the help of post tension tendons. Such architectures functions effectively without disrupting the traffic moving under it and also reduces the impact on environment significantly.

Post tension tendons are made of prestressing strand, anchorage, ducts, and grout and corrosion protection materials. Since this technology is new therefore there are no inspection systems for tendon components. Recent cases of corrosion of post tension tendons in complex bridges have become a significant problem.

After getting information about tendon corrosion, department of transportation has inspected their post tension structure inventory to assess and quantify the rate of tendon corrosion and to estimate the remaining lifespan of the affected member.

Infrastructure Preservation Corporation (IPC) has developed a comprehensive post tension tendon inspection service named “TendonScan®” which utilizes non destructive testing and evaluation methods that can find corrosion and section loss within a PT tendon. 

What it is?

As we have mentioned above that it is a comprehensive tendon scanning system which works on non destructive testing principals to find out voids, water intrusion and bleeding grout in external tendons. This system also includes a device to detect section loss within the tendon.

Why was it developed?

During construction of complex bridges, tendons are filled in grout to prevent corrosion. But during grouting process, the grout tends to separate depending on grout’s quality, admixtures, pumping equipment and procedures. This separation result into low pH grout at tendon points and anchorage which made these locations susceptible to corrosion.

Complex bridge inspection is incomplete without tendon testing therefore we have developed this TendonScan system to resolve this problem.

How it is used?

It is a battery operated robotic system that uses the latest in non destructive testing and modern technology. This system couples itself with the tendon and travel along it to perform a MRI like inspection of the material inside it. The inspector stands on the mobile control unit which travels along with the sensor. The sensor works through wireless connectivity to transmit the collected data. The information is transferred to control station for real time assessment of the tendon condition. The image of internal section of tendon is then illustrated in 3D color graphics so that any discontinuity like water intrusion, void or bleeding grout can be identified and quantified easily.

What problem does it solve?

This tendon assessment system helps in locating corrosion, voids, bleeding grout, section loss and other problems inside and outside the tendon. Moreover, it also helps in monitoring the discontinuities over a period of time which helps in deciding that when to repair or replace a post tension tendon. 

To know more about our products and services, you can visit our website https://www.infrastructurepc.com/ or contact us at info@infrastructurepc.com.

Introduction to BridgeScan

Infrastructure is the backbone of our nation’s economy. The ability to get to work on time, get goods to market and safely travel relies on the condition of our infrastructure. Our nation’s infrastructure averages over 50 year old and is ageing and deteriorating at a faster pace than they can be repaired. Although the infrastructure is required to be inspected at regular intervals the inspection methods have not kept up to allow the asset owners to properly maintain them. If infrastructure is maintained properly on regular intervals, then its service life span can be extended. Infrastructure Preservation Corporation (IPC) provides inspection services through non-destructive testing methods and robotic engineering. We have patented technologies for various specific needs related to inspection and monitoring issues of the different structures like bridges, roads, high mast light poles and more says Doug Thaler, Exec. Vice President.

Here we will discuss some features of our in-house technology BridgeScan®.

What it is?

It is a patented bridge deck inspection service which utilizes non-destructive testing methods to cater following needs

• Identify rebar pattern

• Locate crack and monitor its progression over time

• Fill density assessment

• Locate delamination, deboning and concrete deterioration

• Abutment water intrusion assessment

• Void detection under approach slab

• Prepare condition assessment report for the asset owner

• Identifies 12 levels of deterioration.

• Conducts bridge deck & approach slab deterioration assessment.

Why it was built?

Traditional method of chain dragging or visual inspection of bridge deck has many drawbacks and limitations like

• It provides subjective results

• Poses risk to public and crew’s life with lane closures and the parking of heavy equipment on the bridge.

• It is time, cost and labour intensive

• Unable to locate delamination from internal layers

BridgeScan® effectively takes care of these problems and has many advantages over traditional methods of bridge inspection

• Offers quantitative results

• Allows the asset owner or DOT to properly allocate assets

• Provides actionable items for repair

• Create 2D and 3D images for analysis

• Accurately create the rebar patterns

• Detect cracks, voids, delamination and deboning

• Reconstruct bridge beam configuration

How it is used?

Although it is a computerized robotic device it is operated by the same bridge inspectors that currently inspect our bridges. Data gathered during the inspection by the device can be analysed in real time without interfering with the integrity or functionality of the bridge’s surface and subsurface.

What problem does it solve?

It detects any kind of minor or major deterioration on super surface and subsurface and creates a detailed illustration in 2D and 3D. Moreover, it stores data for later analysis and works on any kind of bridges old and new. The bridge does not need to be closed and traffic can move easily during bridge inspections.  All bridge inspections conducted by IPC are conducted within the DOT’s (Department of Transportations) current maintenance budgets.

To know more IPC and their products and services, check out their website https://www.infrastructurepc.com/ or contact them at info@infrastructurepc.com.

Modern technology and robotics can save billions in infrastructure cost

The world has become a global village because countries are now interconnected, more people are travelling and business is expanding in multiple nations. All of these things are happening at an ever increasing pace and to stay competitive on the world stage today our infrastructure needs to keep up. Without a modern, safe infrastructure our ports will not be able to handle the new deep water cargo ship, goods will not be transported from factories to shipyards in a timely manner and people will be constantly late for work. Today more than ever, growth and development is not possible if the nations infrastructure lags behind.

In the 19th and 20th century, America focused mainly on expanding its transportation network by building roads, bridges and other concerned structures. But the inspection and maintenance of those structures have not kept pace. Many of those structures entered the end of their useful life years ago. Traffic loads are 10 times what they were when some of these structures were built. Because they now support more traffic, the loads place additional wear on them. In addition, due to antiquated inspection methods the corrosion and deterioration has outpaced repairs. Due to this deterioration we need to find alternatives to just replacing or re-building these structures.  There is just not enough money in the system to replace all of the bridges for example that are in a state of disrepair.

How modern technology and robotics can revive the infrastructures?

Use of technology and robotics is a proactive step in the maintenance of our infrastructure. For example, if you know that you are having symptoms of any disease in its initial stage then you can effectively treat the disease and regain your health. Similarly, if we know where deterioration, water intrusion and corrosion  is occurring in a structure we can make the minor repairs to them before they become a threat to the whole structure(Movable Bridge Inspections).

Modern technology plays a major role in inspecting the deterioration and other deformities developing in the structure. It accurately assesses the condition of a structure like bridge, road, dam, tunnel in a non destructive manner. In traditional might I say the current antiquated methods, inspections are performed on selected areas which is known as lot sampling and samples are collected through methods like coring and cutting which is a destructive method. Once you core or cut we are exposing these areas to air and moisture which further causes corrosion. 

The inspection and monitoring process of infrastructure needs to change. With todays modern technology and robotics we have the capability to make our inspection processes more accurate. Modern robotics integrated into the inspection process can not only provide more quantitative data but can prevent lane closures, increase the safety of both the inspectors and the public and more accurately assess the infrastructure they are inspecting.

Modern technology combined with robotics has many advantages over traditional methods of infrastructure inspection and maintenance. Some of the benefits are:

• No more lane closures or temporary closing of the bridge

• Eliminates the need for night time inspections

• Increased safety of public and inspection crew

• Quantitative results instead of subjective results

• Real time data analysis on site

• Data history of structure condition can be stored for later detailed analysis

• Accurate condition assessment of surface, super surface and sub surface layers

• Determine density of concrete cover and location of rebar without damaging the surface 

• Find out minor cracks, voids, water intrusions inside the surface and visualize it through 2D and 3D illustrations

• Reduce labour expenses and saves time

• Collect data from dangerous heights from every angle with the help of robotic equipments

• Thoroughly check each and every component of the structure and find out more minor and major problem areas as  compared to visual inspection

• Helps in recommending and prioritizing the repairing work

Infrastructure Preservation Corporation is determined to provide utmost safety to public and staff during bridge and road inspection and provide accurate condition assessment report to the Department of transportation and bridge owners. Therefore, we use customized and patented products for inspection and monitoring of the infrastructure that we are tasked with inspecting.  We use experienced certified bridge inspectors along with robotics to offer the asset managers a far better deliverable then they have ever received before. For example, we have CableScan® which utilizes robotic technology to gather detailed information of a cable stayed bridge in short time. Similarly, we have additional advance technologies developed in house like PoleScan®, TendonScan®, CrackScan® and others which reduce not only reduce the cost of bridge inspection or inspection of any other structure significantly, but provide the quantitative data the department of transportation needs to allocate assets.

Infrastructure Preservation Corporation will provide a free estimate of our inspection services. If you want to find out more about our services go to https://www.infrastructurepc.com/ or email info@infrastructurepc.com.

Insights Of Bridge Preservation

Rise in number of vehicles with each passing year has affected the environment but it has also increased the load on nation’s bridges and roads. Extra load and other environmental factors like leaking joints or chloride penetration from salt water further damage these bridges and reduces their service life.

Much of the  infrastructure has been built in the United States at the beginning of twentieth century when cars were becoming more popular and transportation was becoming critical to an industrialized nation. But with passing decades, development of new infrastructures slowed down while the existing structures reached their mid and end of expected life. Fatal accidents like Silver Bridge collapse in 1967 in West Virginia and Mianus River Bridge collapse in 1983 in Connecticut have drawn the public and government attention towards the poor conditions of existing infrastructures like bridges, roads, tunnel, dams etc. and numerous inspection and bridge preservation programs came into action.

Bridge Preservation consists of Bridge inspection, through maintenance and timely repair which help in extending the service life of bridges. Bridge preservation is a systematic approach involving inspection and repairing of a bridge and its components with non destructive testing methods.

Bridge preservation program may include these following processes

• Deteriorated concrete repairs

• Bearing replacement

• Structural steel repairs

• Bridge superstructure Jacking

• Deck surface repairs

• Bridge joint replacements

• Pile repairs or replacements

• Concrete sealers or overlays 

Infrastructure Preservation Corporation (IPC) offers products and services using non destructive testing methods to assess structural stability of any infrastructure by finding any deterioration, cracks, voids, water intrusion etc. in bridge super-structure and sub-structure and provide condition assessment report with recommendations for the repair.

IPC’s inspections integrate modern technology and robotics with experienced bridge inspectors to supply quantitative data unlike anything seen before. Says Doug Thaler, Partner in IPC. Our quantitative results obtained from our in house patented modern technologies are easy to understand with its 2D and 3D graphical illustrations. The results provide the asset owners or department of transportation to better allocate assets, Thaler continued. Bridges are inspected on an every two year cycle with deficient bridges being inspected every year. Without integrating modern technology into the inspection process, bridges will continue to fail.  With non destructive testing methods being utilized on an entire bridge deck or post tension tendon, problems can be identified early and repairs can be prioritized to keep our infrastructure and public safe.  “Our team of expert and experience engineers and staff provides accurate condition assessment report of the whole structure and also the detailed report of the components like cable stays or post tension tendons, even high mast light poles. We also offer mechanical and electrical inspection of the movable bridges/draw bridges. Our emergency service gives you detailed report of your bridge or road in shortest time period and without interrupting the ongoing traffic on the bridge.

IPC offers greater safety to the public and the inspection crews during the bridge inspection with our non destructive testing technologies. With their advanced technologies, IPC is able to look out for any deteriorations visible to the naked eyes and also damage beneath the surface which are generally not found during visual inspection. Our automated devices saves time and labour during inspection and our inspector is able to check all the data in real time with our computerized outputs which are stored for later analysis and also to check deterioration progression from future inspections.

For further information about our services and products, leave us a message with your contact details on our website https://www.infrastructurepc.com/ and we will get back to you as soon as possible. Subscribe to our newsletter at our blog www.infrastructurepc.com/robotics to get the latest updates and visit our site to get all the information in detail(Ground PenetratingRadar).