Wide-Flange Beam to HSS Column Moment Connections

Hollow Structural Sections (HSS) are efficient members to use in a variety of applications, including moment frames.  When the beams and columns are HSS members, moment connections can be designed using the provisions in the American Institute of Steel Construction (AISC) Specification for Structural Steel Buildings Chapter K.  The tables in Chapter K cover various connection configurations and provide the limit states with the applicable strength equations.  When the beams are wide-flange sections and the columns are HSS, there are multiple options for moment connections and these will be discussed in this article.

It is important to remember that connecting to an HSS column is different than the considerations of connecting to the flanges of a wide-flange column.  The moments in the wide-flange beams are resolved into concentrated forces at the beam flanges that must be transferred into the column.  The main difference between an HSS and wide-flange column is how the forces from the beam flanges are transferred into the column webs to be resisted as shear.  In a wide-flange column, the web (and thus the stiffness) is located at the center of the column flange.  In an HSS column, the forces applied to the column face must be transferred to the side-walls, which act as the webs.  Due to the fact that HSS walls are generally thinner and must transfer the forces to the sidewalls, the thickness of the HSS column wall becomes a critical consideration for the strength and stiffness of a moment connection between an HSS column and a wide-flange beam.

Given these considerations, the common connection types discussed in this article and the recommendations that accompany them are generally aimed at having the concentrated forces from the beam flanges applied as close to the sidewalls of the HSS column as practical.  Two general recommendations can be made for all connection configurations; design the column to eliminate the need for reinforcement at the connection and keep the ratio between the column width and the beam flange width close to one.

When possible, the connection configuration and forces applied to the HSS columns should be considered when selecting the column size.  Thicker walls and/or narrower column face dimension can strengthen and stiffen the column wall and remove the need for costly stiffeners or column reinforcing.  Put more simply, it is typically more economical to have heavier columns than to have reinforced connections.  This is true of connections with wide-flange columns as well.  There are requirements for applying concentrated forces to the flanges that may lead to stiffener or doubler plates at the moment connections (when the column web or flanges are not thick enough).  AISC recommends using heavier column sections to avoid costly connection reinforcement.

The second recommendation is to keep the column width and beam flange width at optimal ratio.  Narrow beam flanges (as compared to the width of the column face) concentrate the force to the central portion of the HSS wall, making the thickness of the wall more critical.

Five of the most common connection types are discussed in this article, but there are several other viable configurations discussed in the resources sited.  This article is focused on low-seismic applications, but there are connections suitable for high-seismic applications.

(This article comes from Steel Tube Institute edit released)

How is the cement pile used as a support structure different from that used as a foundation pile?

How is the cement pile used as a support structure different from that used as a foundation pile?

The requirements of the force characteristics of the pile is different. The stress of the foundation pile is characterized by the decrease of the pile stress with the increase of the depth, so the pile foundation of the pile is also larger. The support pile is different, such as cantilever structure, the pile at both ends of the pile at both ends of the shear force and bending moment is small, the second half of the force, so the pile body force two small middle.

Holding layer and base. Foundation pile often choose a better soil as a pile end bearing layer. And in order to make the pile bottom and the holding layer to better integration, usually have the base requirements, that is, after the drill bit to reach the bottom of the pile, do not enhance the original spray mixing 30 ~ 60s, so that the pile end and soil have a good contact. Cement soil support pile is no such requirement.

Pile head. The quality of the pile head is very important for the base pile, often by re-stirring, increase the amount of cement and other means to increase its strength, and usually 0.3 ~ 0.5m poor quality of the pile head removed. Support pile in addition to the pile to set the crown beam, plus top support, the general no such requirements.

Pile form. The use of the function determines the support pile usually overlap with each other into a concrete wall, the surface of the pile in the form of wall-like, grille and block, the pile in addition to the form of these pile, but also the form of column-like pile. In addition, the foundation pile is usually in accordance with the different soil to take the length of the pile in combination with the form of pile, and the length of the support pile is usually the same, or sometimes on the small variable cross-section form.

Offset. Cement pile as a foundation pile usually forms a composite foundation with the soil between the piles, usually allowing the pile to have a deviation of 50 to 200 mm. When used as a support pile, especially as a water curtain, the pile is very easy to cause leakage after the leakage, so the requirements of the pile position is very strict, usually not less than 50mm.

HZ 575 A, HZ 575 B, HZ 575 C, HZ 575 D, HZ king piles

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HZ king pile value of the maximum allowable plastic moment AZ 13 or AZ 13 10/10 or AZ 18.; PL is automatically calculated by the program using the following formula: Design penetration of the piling is based on a factor of safety for HZ 575 A stability applied to soil strengths. We can look at the joint slippage by following these steps. Right click on the wall and select Show Values → Joint Shear Displacement. PL is -12 used in the diagram of the moment to help the user to check if the maximum design moment is reached or not. To avoid compounding factors of safety, the HZ 575 B sheet piling and wales are designed to resist forces produced by soil pressures calculated using a factor of safety of 1 for both active and passive pressures.See Figure 4.9 for the definition of the other HZ king piles parameters. Moment-Curvature Diagram (M-N-Kappa) window for a plastic sheet piling calculation (2 branches)To remedy this, right click on the -14 wall and click Select Support Layer. Click under the Joint heading and select ‘negative side: Joint 1’. Name. The HZ 575 A and HZ 575 B name of the section can be changed in -12 and -14 here if desired. Section bottom level. Consequently, the analyses for soil pressures and system stability must be repeated with full soil strength properties including consideration of usual, unusual, and extreme loading conditions. kmod is the modification factor, γM is the material factor, fMmax is the reduction factor applied to the maximum moment. The limit value M design; You will see values only at the very bottom of the HZ 575 C wall. This suggests that we are seeing the slip on the left side of the wall rather than on the right.

Enter the combined walls co-ordinate of the bottom of the AZ 18 10/10,AZ 26, AZ 26+0.5, in relation to the reference level. Note: Sheet piling length may not be larger than 100 m. Thickness The thickness of the sheet piling profile, i.e. the height of the crosssection. Elastic stiffness EI Enter the flexural elastic stiffness of the section, called EIelastic.

The sizes of the sheet piling and wales are RZD 16, RZU 16,RZD 18 determined from the net pressure distributions, depth of penetration, and assumed structural supports as illustrated. Symmetric Mark this option in case of a -24 symmetric moment-curvature diagram.m a. Cantilever wall. Bending moments and HZ 575 D shears are calculated under the assumption that the wall is a cantilever beam fixed at the bottom of the wall. Use several sections if the bending stiffness varies along the vertical axis of the sheet piling. Click OK. You will now see the shear displacement between the joint and the soil to the right of the wall.

Anchored wall. (1) Structural analysis. Bending moments, shears, and anchor force are calculated under the assumption that the wall is a beam with simple supports at the anchor elevation and at the bottom of the wall. Enter the plastic moment of the positive part of the moment-curvature diagram (in compression), called Mpl. Finally, we can look at the HZ 575 C, or HZ 575 D in the -24 or -26 sheet pile RZU 18,RH 16, RH 20 wall. Right click on the wall and select Show Values → Bending Moment. You can see a maximum moment of ~64 kNm. Young’s Modulus E and moment of inertia I) per running meter if it has not already been imported from a library.

Plastic moment positive With the bottom of the combined wall at the penetration consistent with a factor of safety of 1, the -26 lateral reaction at the bottom support will be zero and the lateral reaction at the upper support will be the horizontal component of the anchor force.

What are the characteristics of soil nails?

The impact of small buildings adjacent to the building. As the soil nail construction using a small step by section excavation, and in the excavation after the timely provision of soil nail and surface structure, so that the surface layer and the excavation slope close integration. Soil nails and the surrounding soil firmly bonded to the soil slope of the soil less disturbed, the impact of adjacent buildings.

Construction tools are simple and flexible construction. The equipment used for the provision of soil nails and the spraying of concrete equipment are all mobile small machinery, mobile and flexible, the required space is also small. Such machinery vibration is small, low noise, in the urban area construction has obvious superiority. Soil nailing construction speed, in the excavation process easier to adapt to different soil conditions and construction procedures.

Good economic returns. According to Western European statistics, soil nailing support than the anchor wall support program can save 10% to 30% investment in the United States, according to its soil nailing excavation patent report can save about 30% of investment. According to statistical analysis of the domestic economy 9 soil nailing works that investment can save 30% to 50%.

Discussion on how to control the foundation pit of steel sheet pile construction

In recent years, with the continuous development of the construction of various cities, the density of urban pipe network construction is also increasing, Larsen steel sheet pile leasing people increased, but in the construction of pipe construction construction Larsen steel sheet pile construction The problem of foundation pit cracks has become particularly prominent. Today, Larsen steel sheet pile manufacturers to talk about Larsen steel sheet pile construction pit cracks how to control.

In the trench construction process there is a more obvious phenomenon, there are Larsen steel sheet pile wall groove 2-3m outside the location of the existence of a longitudinal horizontal cracks, and the geological situation is better groove side of the wall is not supporting the project Paragraph basically does not exist this phenomenon.

We mainly make a brief analysis of the formation of this crack in order to be able to more objectively understand the causes of cracks and master the measures of crack control, so that Larsen steel sheet pile lease to normal operation. The excavation and unloading of the pit during the excavation of the foundation pit causes the maintenance structure to produce horizontal displacement under the pressure difference inside and outside the envelope, causing the deformation of the outer soil of the envelope, which causes the settlement of the outer structure of the foundation pit, and The unloading of the foundation pit will also cause the uplift of the pit soil.

It is believed that the movement of the strata around the foundation pit is mainly due to the deformation of the envelope and the uplift of the pit. The most direct reason for the movement of the trenches around the trenches is the horizontal displacement of the surrounding walls. When the trenches are shallowly excavated, they are not provided with support for rigid strength (such as cement- (Such as Larsen steel sheet pile, underground continuous wall, etc.) are the largest wall displacement, the direction of the horizontal direction of the trench was triangular distribution, cracks will not occur in the pit outside.

The main road of the city has the function of distributing traffic and service. The buildings on both ends are denser, the groundwater level is high, the soil is mainly silt and saturated soil, the underground pipeline is complicated and the geological environment is bad. The Larsen steel sheet pile high strength, the pile between the pile tightly connected, good water barrier, can be reused, apply to the section; so the road support the use of Larsen steel sheet pile. However, the longitudinal cracks in the pit outside the support of the Larsen steel sheet piles have some safety risks for the underground pipelines and the surrounding buildings. We must pay attention to the unnecessary losses, and make the following suggestions to control the deformation and cracks:

  1. Increase the depth of the Rosen steel sheet pile;
  2. Increase the envelope and support stiffness;
  3. According to the actual situation to strengthen the pavement passive area soil;
  4. Reduce the excavation support time, with the excavation with the lower tube to reduce the trench exposure time;
  5. The influence of precipitation on environmental deformation is controlled by the depth of the envelope and the layout of the drainage wells.

Do the above points, while strengthening the monitoring to ensure the safety of foundation pit construction. With the continuous progress of the project, and constantly strengthen the construction technology summary and on-site management, the use of more scientific methods to optimize the construction side of the proposed construction program to ensure that the construction quality control construction costs, through the unremitting efforts of all staff to protect the heating pipe network and heat Station works can be safe and smooth, the quality and quantity of the completion.

Design Considerations of Helical Anchors

Helical anchors are a factory-manufactured steel foundation system consisting of a central shaft with one or more helix-shaped bearing plates, commonly referred to as blades, welded to the lead section. Extension shafts, with or without additional helix plates, are used to extend the anchor into competent load-bearing soils. Helical anchors are advanced (“screwed”) into the ground with the application of torque.

The terms helical piles, screw piles, helical piers, helical anchors, helix piers, and helix anchors are often used interchangeably by specifiers. However, the term “pier” more often refers to a helical foundation system loaded in axial compression, while the term “anchor” more often refers to a helical foundation system loaded in axial tension.

(This article comes from AquaGuard Foundation Solutions edit released)

What Is Soil Nailing Wall Construction?

Soil nail wall construction is a technique used to bring soil stability in areas where landslides might be a problem. Soil nail can prevent landslides by inserting steel reinforcement bars into the soil and anchoring them to the soil strata. It is called Soil Nail because it’s like having a nail being hammered into the soil, where the nails, are the steel bars.

Depending on the complexity of the work, soil nailing can be ranging between $80 per square feet up to $200 per SF. Some contractors will use a software called Snail Plus to determine their design and complete preliminary assumptions on the soil nailing.

(This article comes from the balance editor released)

Faster Tieback Walls with all the Practical Advantages of Helical Anchors

Immediate pull testing of helical tieback anchors after installation serves as a check on design procedures and eliminates deflection at working loads.

No delays because there is no grout

  • Typical production rate of 30 to 40 per day for installing and testing
  • No holes to drill
  • Cuts labor and equipment costs
  • Can save 30% while obtaining high anchor-load capacities

Solves construction problems

  • In cohesive soils, no belled and/or long sockets
  • In non-cohesive soils, no casings or grouted sockets
  • Bearing mode (not friction mode) anchors
  • No de-watering for below-water-table applications

(This article comes from CHANCE editor released)

What Is Micropile

Micropile is another type of pile which is act as a supporting structure to transfer the load from the building to the ground. As the name implies, micropile is small diameter piles constructed by the drilling process and are often keyed into rock. There is various diameter of micropile can be found in the market ranging from 100mm to 250mm. Of late, technological advancement in machinery has made it possible for micropile of much greater diameters to be constructed.

(This article comes from pile-driving.com edit released)

In the construction of steel sheet pile, how to deal with the adjacent sheet pile

This phenomenon often occurs in the soft soil plate pile, when faced with unknown obstacles, rock or pull pile tilt, etc., the sheet pile resistance increases, will bring the adjacent sheet into the pile. Can be handled as follows:

  1. Not once the plate pile hit the elevation, leaving part of the ground, until all the pile pile soil, with the screen to the rest of the people hit the soil.
  2. The adjacent sheet pile welding in the rub on the rub.
  3. Several pieces of sheet pile are joined together by steel.
  4. In the connection lock mouth coated with butter and other grease, reduce resistance.
  5. The use of special plugs to prevent the sand into the connection lock.

After the sheet pile is brought into the soil, the same type of sheet pile should be welded at the top to supplement the insufficient length.