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Steel Screw Pile Foundation

Jim Houlette — Thu, 19 Jan 2012 21:00:31 +0000

A deep foundation system that is gaining popularity in areas with difficult soil, contaminated soil and due to its speed of construction is steel screw piles.

At first glance screw piles look like the typical helical pier. However, there are significant differences that make a dramatic change in capacity. First, the screw piles are installed as a single continuous piece in lieu of sections bolted together. Second, the machinery used to install screw piles is larger and capable of producing a higher torque.

The components of a screw pile are simple; a steel shaft, steel helix at bottom of shaft, and a connection plate at the top of the shaft. Screw piles can vary in size to accommodate different design loads. The steel shaft size is a function of axial load, torsion during installation and thickness due to corrosion. The helix is a plate that is shaped just like the threads of a wood screw and engages the soil to distribute the axial load and it locks into place to provide tensile loads as well.

One of the first questions people have is, “How long will it last until failure from corrosion?” There are several factors that go into corrosion of steel; oxygen, moisture, dissolved salts and other corrosive chemicals. Since there is very little oxygen in the soil, corrosion is limited and can be controlled by using thicker material to allow for expected corrosion. The life of steel screw piles can be 50 years to an indefinite period depending on the type of structure and life span needed.

I designed foundations in Stapleton where the site was located over the old terminal and contaminated soil was discovered. If typical straight shaft drilled piers were used the spoils from drilling the hole would have had to been bagged and disposed of properly. To avoid bringing contaminated soil up to the surface steel screw piles were used.

I list a lot of PROS below and for good reason. I have been very impressed with screw piles and the wide range of uses of them. EVstudio was recently visited by Alpine Site Services for a lunch and learn. Mike Oliveira discussed how screw piles are installed and the many advantages to their system over other typical foundation types. What really impressed me was the speed of placement of screw piles. Alpine can place 30 to 50 screw piles in one day!

Another great advantage to screw piles is that they can be placed at an angle to provide bracing and tension resistance that is aligned with the force of the tension. An example is a typical counterfort that braces a foundation wall. You can see the angled screw pile above.

PROS
Fast Installation
Can be Proof Tested
Negligible Uplift Pressure from Swelling Soil
High Capacity up to 500kips
High Tensile Resistance
Made from a reusable material (LEED point)

CONS
Specialized System
Large Equipment
Concerns with Corrosion

Learn more about different foundation types.

Originally posted 2009-10-10 00:21:43.

Killeen Landscape Frontage Standards

John Olson — Thu, 19 Jan 2012 20:59:32 +0000

As I was reviewing the landscape standards for the City of Killeen, Texas, I noticed some major differences in the requirements in respect to other City's standards. The difference I will talk about in this post is the spacing of trees along the street right-of-way. In Killeen, a development is required to have one tree for every 25-feet of street frontage and one shrub for every 5-feet of street frontage. This standard is much higher than other municipalities for frontage. There is some relief for properties with two frontages where the City will allow one tree for every 30-feet.

Typically, the tree spacing can be alleviated by staggering the trees on each side of the sidewalk, providing for greater linear distance. However, it seems from the code that locating trees in the public right-of-way requires additional approval from the Building Official AND City Engineer. Many engineers are apprehensive about locating trees in the tree lawn due to the potential for roots cracking the sidewalk. Previously, I wrote a blog about this subject titled "Urban Street Trees: Root Barrier". A link to this blog post can be found here.

I have illustrated two variations where the landscape standards are met. The first image shows all of the trees aligned along the sidewalk, 25-feet apart. The second image shows some trees staggered into the landscape islands. One unique aspect of the code, as I have read it, is that there is not a requirement for trees within the islands of a parking lot. Therefore, the use of the landscape islands for trees can alleviate the separation of trees along the frontage.

This illustration shows the trees spaced at 25-feet on-center along the frontage.

This illustration shows the utilization of the parking islands for occasional relief of tree spacing along the frontage.

Tree selection is very important with requirements such as these. A common street tree, like a Bur Oak (Quercus macrocarpa), has a mature canopy of 65-feet. With 25-foot minimum spacing of the trees, assuming all of the trees along the street are Bur Oak, the canopies would encroach into each other limiting the tree's health. In this situation, the landscape architect would either choose a different tree or cluster smaller trees in one area to increase the distance between trees along the remainder of the street. Occasionally, street trees have many different cultivars. If an upright (or fastigiate) cultivar can be found, it would be recommended in this situation.

Originally posted 2010-05-06 00:01:41.

Community Based Clinic for US Army Medical Command

Gene Dane — Sat, 31 Dec 2011 21:20:39 +0000

In an effort to provide our US Army Soldiers and their families with better access to health care services, the US Army Medical Command (USMEDCOM) has initiated the Community Based Clinic program. As the name would imply, this program takes the health care facilities that would normally be located on the US Army Installation and places them "outside the fence" in the communities surrounding the installation.

Our Copperas Cove office of EVstudio recently completed the architectural and engineering design service phases for the USMEDCOM Community Based Clinic located in Killeen, Texas near Ft. Hood, Texas. The facility is approximately 13,ooo square feet, on a two acre site, and is designed to accommodate a staff of 35 US Army medical personnel.

The facility has 18 exam rooms, a fully equipped treatment room, an on-site laboratory, pharmacy, behavioral health unit, dedicated pediatric practice spaces (including an immunization room), 2 group practice areas, multiple triage areas, and administrative spaces.

In addition to the features that would be expected in most private sector clinics, the USMEDCOM facility also incorporates many of the same AT/FP (anti-terrorism / force protection) considerations that would be found in facilities located on a US Army Installation. EVstudio worked directly with the US Army Corps of Engineers and the staff of the US Army Medical Command to insure this facility met all the crucial design criteria standards established for this facility type.

The Killeen, TX Community Based Clinic has been designed to meet LEED Certified standards. We have incorporated numerous energy and water saving strategies into this facility along with site development considerations and a focus on indoor environment quality.

EVstudio takes great pride in designing facilities that will provide a better quality of life for those men and women, along with their families, that serve our country.

Originally posted 2010-12-29 00:43:50.

Raft Slab-on-Grade Foundation

Jim Houlette — Sat, 31 Dec 2011 21:20:36 +0000

A Raft Slab-on-Grade foundation can be as simple as a 4” thick slab with no reinforcement and a shallow perimeter rib to an 8” thick slab heavily reinforced with deep ribs spaced roughly 10’o.c. The wide range of concrete thicknesses and reinforcement is a function of many things such as soil type, loads, exterior finishes, allowable deflections, climate, and many more factors. The primarily factor that influences the slab thickness, reinforcement and rib sizes of a slab-on-grade foundation is the soil type.

If the soil is a sandy material with non-swelling fines to allow good compaction then the slab-on-grade foundation will be evenly supported, and has a low risk of soil movement. This raft foundation will just need the minimum slab, ribs and reinforcement.

If the soil has swelling material that is susceptible to changes in moisture content then the raft must be designed to resist this movement. The use of reinforced ribs is an economical way to strengthen the slab. Ribs are below the slab and are spaced evenly to create a grid or waffle appearance. This is done in lieu of thickening the entire slab because you gain more strength with depth and will typically use less concrete and steel reinforcement to achieve the same design capacities.

Raft foundations have been used for residential structures, commercial structures and heavy construction structures. The reason for the wide range of uses is simply because the raft slab-on-grade foundation is simple to construct and one of the most cost effective foundations. Typically, little earthwork is needed, sites are leveled, ribs are trenched, reinforcement placed and then concrete is placed. Also, since the raft foundation is just reinforced concrete, access to plumbing can be achieved by removing sections of the slab and then patching as needed. If the slab is post tensioned then accessing the plumbing is much more difficult.

But the raft foundation has its problems as well. On sites with high risk of soil movement the slab can become expensive if deep ribs and heavy reinforcement is needed. That is when a post tensioned slab may become cost effective. In addition, the control of visible cracks in the slab can be difficult. Concrete shrinks as it cures and if control joints are not placed appropriately or sufficient reinforcement is not used the owners may be upset with visible cracks. Cracks caused by shrinkage do not indicate failure, but can be an eye sore and a difficult conversation with the owner.

PROS
Cost effective
Common Construction
Low Tech
Sections may be removed to Access Plumbing

CONS
Limited Design Capacity
Does not respond well to Soil Movement

Learn more about different foundation types.

Originally posted 2009-11-03 10:42:22.

Designing for Alzheimer’s Disease

Rich Muller — Mon, 12 Dec 2011 23:46:18 +0000

A recent assignment has come in for a building to host people who are suffering from memory loss related diseases. The facility, which is in Texas, falls under the assisted living use category and therefore needs to address certain aspects of the International Building Code as well as the requirements of the Texas Department of Aging and Disability Services. Beyond the code issues, there are a host of memory care specific program components and philosophies which need to guide the design process to create a successful project. In this case, success is judged by how well the facility functions from the point of view of the nurses, administration and, most importantly, the patients.

Each state sets requirements for public health projects. Fundamental to this is the classification of who will occupy the facility, how many patients will there be and how long they need to stay. In our case, the client intends to offer overnight accommodations to the patients. Therefore the facility falls into the assisted living category, as opposed to the adult day-care category. This distinction drives a multitude of requirements ranging from how much space each resident is provided, the type of kitchen, which sections of the Life Safety code to follow, the furnishings, the program, the circulation, etc.

Further, the clients would like to provide rooms for up to 48 residents. This places the project into the ‘large’ facility (the number in Texas between large and small is 17 residents). In addition, since the residents may require staff assistance when evacuating, the project is pushed into a Type B facility and therefore requires conformance to Chapter 12 within the National Fire Protection Association (NFPA 101).

Once the code analysis is understood, we can let the code edicts help inform the design phase. Central to this is circulation and egress. For example, from any point within the building which is accessible to residents, an eight foot corridor is provided for circulation and egress. Should an evacuating event occur, residents and staff will need eight feet to fit two gurneys or wheelchairs side by side to leave the building. In addition, resident rooms need to have a one hour fire separation between their rooms and the assembly space common to the rest of the residents. Given these two main constraints and incorporating the program set by the client, the following plan was conceived:

Floor Plan For Texas Memory Care Facility

This U-shaped plan is a classic response to the demands of the program. The central core is flanked by two wings. Within the core, we build the entry and administrative functions into the front portion. The front portion, shown in pink, also hosts the kitchen and back-of-house program. Beyond this, the residents and their guests enter into the main common space which hosts the activity area, the dining area and the nurse’s station. This area is shown in light purple. It is here where the residents will spend most of their day. Since many memory care patients are in need of supervision and have limited access to the outdoors, the design of this space emulates the feeling of being outside. Not only is there a wall of glass along the back for visual access to nature, but the soaring ceilings and abundance of windows above the main hall represents the sky and allows for a feeling of vertical space above and the passage of sunlight through the upper windows. The overall effect creates a sun-filled, cheerful, active space.

Flanking the central area are two residence wings, shown in light yellow. Fashioned after a ‘neighborhood’ concept, be it by color theme, material theme or personalized touches, each hall presents the residents with a smaller scale to manage in finding their room and conducting their private lives. Within their rooms they find a refuge from the activities of the main hall and are afforded a quiet space to meet with loved ones, converse with co-residents or pursue their own ends.

At the end of each residence hallway, there are a set of double doors which allow access to a deep covered porch and the self-contained courtyard, shown in green. It is here where residents are encouraged to step into the outdoors, get a breath of fresh air and take in nature.

In particular to a memory care center, there are several built-in yet tacit provisions that, while may seem to be innocuous to the casual observer, are highly designed to help the particular end-user.

Among these are way-finding guides which help orient the resident to where he is and where he needs to go. Simple things like placing a clock over one residence wing and a picture of a landscape over the other help the resident determine where he needs to go. Another feature is preventing direct glare in lighting situations from further disorienting the resident. For this reason, long corridors do not terminate in a set of double doors which would allow sunlight to bounce off the floor and into their eyes. To the same end, the walls and floors are treated with non-reflective surfaces, walls are painted in cheerful, but not overly bright colors, and headlights from visiting cars are not allowed to shine directly into a resident’s room.

We have also incorporated a circular walking path within the building. Many memory care patients have a compulsive trait of rocking on the feet or rubbing their hands and are need of some form of constant motion. A circular walking track addresses this need. Our is fashioned out of the perimeter of the common area. The residents can walk around the loop, while still feel like being part of the group since they are walking around the dining and activity rooms as well as the center of their world, the nurse’s station. This sort of controlled wandering allows the nurses to maintain supervision of their charges.

The above points along with a host of other features and on-going research into this field will hopefully serve those who are suffering from memory loss diseases. A successful memory care facility must place the patient foremost in the thousands of design decisions that go into creating a welcoming, safe and positive center.

Rendering of Texas Memory Care Center

Christian House of Prayer (CHOP) Civil Engineering

DJ Zehnacker — Tue, 22 Nov 2011 08:09:43 +0000

EVstudio Civil Engineering has recently completed civil construction drawings for a major development/expansion to the existing Christian House of Prayer campus located in Killeen, Texas. The project consists of a new lecture hall, a strip retail area, and major drainage and utility improvements throughout the 64 acre site. Although the project had it's challenges (as most do!), the entire design process went smoothly due in large part to the fact EVstudio handled the architecture, civil engineering, landscape design, lighting design, planning, and structural engineering all in-house.

Below is an exhibit which shows the existing church and parking lot and the proposed lecture hall, retail retail area, and infrastructure improvements:

Christian House of Prayer - Overall Site Exhibit

: An overall look at the 64 arce site

Map for EVstudio’s Texas Architectural Office in Copperas Cove

evstudio — Mon, 21 Nov 2011 08:02:25 +0000

If you're already in Copperas Cove, our office is easy to find, just off 190 at 913 South Main Street.

If you're not familiar with Central Texas, our office is north of Austin and west of Temple, within easy driving distance of the major Texas cities.

Originally posted 2009-06-02 00:05:59.

Location Efficiency as the Framework of Activity Centers

John Olson — Mon, 07 Nov 2011 18:39:32 +0000

The convenience factor, or Location Efficiency, is often a forgotten component of development in a society that has become increasingly automobile dependent. Development occurs with the assumption that people drive and will always get in a vehicle. Location efficiency can be defined as the ability to access the daily basic needs with little or without the use of the automobile. The United States Partnership for Sustainable Communities was created with location efficiency as a foundational element by an inter-agency partnership between HUD (or Department of Housing and Urban Development), DOT (or Department of Transportation) and the EPA (or Environmental Protection Agency). Several advocacy groups, such as the Center for Neighborhood Technology and the Congress for the New Urbanism have relied on this as a foundation for their organizations since their inception.

The United States is beginning to better focus on location efficiency with development as we consider the triple bottom line, that is People, Planet and Profit. In considering the basic human needs, new development has the ability to become holistically sustainable. At EVstudio, we are currently in the process of finalizing construction drawings for a new 10,000 square foot Lecture Hall and over 22,000 square feet of commercial space for Central Texas' Christian House of Prayer (CHOP).

Places of worship, such as CHOP, understand that convenience is a key component to the congregation. Convenience is important to the principles of creating a Place for Worship; a Place of Learning; a Place of Enrichment; a Place for Friendship; and a Place for Service. A community who worships, learns and serves together create an enriching and friendly environment to spend time. CHOP in Killeen, Texas will soon become an even greater community than it already is today. The ability to park once with access to breakfast, worship, conversing with friends, shopping, dining, playing and attending events at the lecture hall is a convenience that is regularly absent in today's society. The future for location efficiency is great for CHOP with the improvements under construction and the potential for future residential capabilities.

Main Street sketch for The Village at Christian House of Prayer in Killeen, Texas. Illustration by John Olson.

The synergies that CHOP is employing are a great model for other activity centers. This opportunity is not limited to places of worship, it can be for a corporate center, military installation, campus and several others.

Ft. Hood Architecture Projects in Progress

Bill Foster — Fri, 28 Oct 2011 06:35:40 +0000

I went down to Texas this week to check out the progress being made on our Ft. Hood projects.

3 Buildings going up.

Soldier Family Assistance Center: Part of the Army's Warrior in Transition program, this will provide services for soldiers including social areas, child care and transitional counseling.

Company Headquarters: Also part of the Army's Warrior in Transition program. This building serves more of an administrative function for the staff that helps with transitioning personnel.

American Water Administrative offices: American Water's new base of operations on Ft. Hood will provide both offices and storage for American Water while they serve the base over the next 50 years.

New Lecture Hall for Christian House of Prayer in Killeen, Texas

evstudio — Mon, 05 Sep 2011 19:06:36 +0000

We recently completed the design of a lecture hall for the Christian House of Prayer in Killeen, Texas. The lecture hall complements their existing facilities and provides an opportunity for collegiate style lectures on their campus. We have also completed design for a neighboring retail center.