The construction of the bridge is extremely good. Every connection and member is in perfect position, and this means that load paths are equally distributed. As we in DIT have learned from our Spaghetti Bridge tests, it is often the best constructed bridge, and not necessarily the best design that wins.

(244 hits)

See the news report here (244 hits).

The model is based on that given in Advanced Analysis and Design of Steel Frames by Li and Li, Wiley 2007.

In Visual C++, the MFC Feature Pack gives the property grid control, but one of the questions regularly asked (see stackoverflow.com) is how to return properties once changes by the user. Part of the problem is the COLEVariant is the return type from the framework, but what if you want a double, or CString for example?

I bashed together a few different ideas and have a nice little functoid that essentially overloads the output type and so this can be used as an argument to your function. The references I used were

• http://www.codeproject.com/KB/cpp/returnoverload.aspx (117 hits)
• http://stackoverflow.com/questions/226144/puzzle-overload-a-c-function-according-to-the-return-value (72 hits)

I defined the functoid in the header file for the CPropertiesWnd class (which contains the CMFCPropertyGridProperty control) as:

1
2
3
4
5
6
7
8
9
10
11
12

class getPropValue
{
public:
    getPropValue(CMFCPropertyGridProperty* pProp):m_pProp(pProp) {};
    operator CString()        {return (LPCTSTR)(_bstr_t)m_pProp->GetValue();}
    operator int()            {return m_pProp->GetValue().iVal;}
    operator unsigned int()   {return (unsigned int)m_pProp->GetValue().iVal;}
    operator double()         {return m_pProp->GetValue().dblVal;}
    operator bool()           {return m_pProp->GetValue().boolVal == VARIANT_TRUE;}
private:
    CMFCPropertyGridProperty* m_pProp;
};

An example call using this is then:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

LRESULT CPropertiesWnd::OnWindowPropertyChanged(WPARAM wparam, LPARAM lparam)
{
    CMFCPropertyGridProperty *pProp = (CMFCPropertyGridProperty*)lparam;
    if (!pProp) return 0;
    CMyView* pView = getActiveView();  // Helper function uses CMainframe
    const int id = (int)pProp->GetData();  // storing property id as a DWORD using SetData
    switch(id)
    {
    case idWindow_OverallScale:
        pView->setScale( getPropValue(pProp) );    // double as an argument to func
        break;
    case idWindow_PenWidth:
        pView->setPenWidth( getPropValue(pProp) ); // int as an argument to func
        break;
    case idWindow_Title:
        pView->setTitle( getPropValue(pProp) );    // CString as an argument to func
        break;
    }
}

There you have it – it could be exactly what you need, or maybe not!

(226 hits)

I’m pleased to say my implementation of the Nelder-Meade Simplex Algorithm (on my C++ page here (240 hits)) was able to optimize it for each minima (depending on the starting locations of course). I did have a weird problem though – starting a solution at (0,0) failed, even though the minima are not equidistant from the origin. Go figure!

The Worst Bridge Collapses in the Past 100 Years (453 hits)

(372 hits)

Mianus Bridge, Greenwich, Conn. (June 28, 1983)

Another collection is here:
http://www.environmentalgraffiti.com/news-seven-quaking-bridges-collapsed-costing-lives (582 hits)

For details of the bridge and the test set-up, see here:
http://nees.unr.edu/4-spanbridges/UNR Web AnnouncementCompositeBridge.pdf (117 hits)

and the link for the webcast is:
http://nees.unr.edu/projects/4span.html (158 hits)

(158 hits)

Four Span Bridge Test

The program is the main point of interst though. For your design, it animates in real time the stresses and member failures that occur as chosen loads traverse your bridge. The graphics are cool and there isn’t too much by way of technical input data required. Prepare to lose some hours playing this though!

West Point Bridge Designer 2010

A funny bridge design is here: